Random crash with GetFeatureInfo on raster outside of the extent of the image (valgrind trace inside)

Tested with the 6.2.0 and with the current state of the 6.2 branch (I can't update to 6.4 for now).

There are some memory errors with valgrind in this particular case (so a random crash). Valgrind test is ok when the GetFeatureInfo point is inside the extent of the raster.

Here is the bad valgrind trace:

```
==4245== Memcheck, a memory error detector
==4245== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==4245== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==4245== Command: mapserv QUERY_STRING=export_geometry=false&y=339&layers=snow_probability&bbox=-50.02584162855885%2C-54.67346707199171%2C179.9%2C80.74744935922759&styles=&service=WMS&x=721&transparent=TRUE&format=image%2Fpng&request=GetFeatureInfo&width=876&feature_count=1&srs=EPSG%3A4326&exceptions=application%2Fvnd.ogc.se_inimage&version=1.1.1&height=516&info_format=application%2Fjson&export_links=1&query_layers=snow_probability&time=2013-10-02T09%3A45%3A00Z&xsuid=1&map=/home/synserv/toto.map
==4245== 
[Thu Oct  3 16:46:55 2013].195760 msProjectRect(): Warning: degenerate rect {139.348011,-8.352165,139.348011,-8.352165}
==4245== Invalid read of size 4
==4245==    at 0x4E0DF1C: msRasterQueryByPoint (maprasterquery.c:1102)
==4245==    by 0x4D3A789: msQueryByPoint (mapquery.c:1608)
==4245==    by 0x4D791C2: msWMSFeatureInfo (mapwms.c:3996)
==4245==    by 0x4D7C9FC: msWMSDispatch (mapwms.c:4992)
==4245==    by 0x4DBB5D3: msOWSDispatch (mapows.c:244)
==4245==    by 0x4E4669C: msCGIDispatchRequest (mapservutil.c:1607)
==4245==    by 0x401129: main (mapserv.c:259)
==4245==  Address 0x96a08f0 is 0 bytes inside a block of size 216 free'd
==4245==    at 0x4A072BA: free (vg_replace_malloc.c:446)
==4245==    by 0x4E0B33C: msRasterLayerInfoFree (maprasterquery.c:167)
==4245==    by 0x4E0DB07: msRasterQueryByRect (maprasterquery.c:960)
==4245==    by 0x4E0DF14: msRasterQueryByPoint (maprasterquery.c:1101)
==4245==    by 0x4D3A789: msQueryByPoint (mapquery.c:1608)
==4245==    by 0x4D791C2: msWMSFeatureInfo (mapwms.c:3996)
==4245==    by 0x4D7C9FC: msWMSDispatch (mapwms.c:4992)
==4245==    by 0x4DBB5D3: msOWSDispatch (mapows.c:244)
==4245==    by 0x4E4669C: msCGIDispatchRequest (mapservutil.c:1607)
==4245==    by 0x401129: main (mapserv.c:259)
==4245== 
==4245== Invalid write of size 4
==4245==    at 0x4E0DF85: msRasterQueryByPoint (maprasterquery.c:1115)
==4245==    by 0x4D3A789: msQueryByPoint (mapquery.c:1608)
==4245==    by 0x4D791C2: msWMSFeatureInfo (mapwms.c:3996)
==4245==    by 0x4D7C9FC: msWMSDispatch (mapwms.c:4992)
==4245==    by 0x4DBB5D3: msOWSDispatch (mapows.c:244)
==4245==    by 0x4E4669C: msCGIDispatchRequest (mapservutil.c:1607)
==4245==    by 0x401129: main (mapserv.c:259)
==4245==  Address 0x96a0998 is 168 bytes inside a block of size 216 free'd
==4245==    at 0x4A072BA: free (vg_replace_malloc.c:446)
==4245==    by 0x4E0B33C: msRasterLayerInfoFree (maprasterquery.c:167)
==4245==    by 0x4E0DB07: msRasterQueryByRect (maprasterquery.c:960)
==4245==    by 0x4E0DF14: msRasterQueryByPoint (maprasterquery.c:1101)
==4245==    by 0x4D3A789: msQueryByPoint (mapquery.c:1608)
==4245==    by 0x4D791C2: msWMSFeatureInfo (mapwms.c:3996)
==4245==    by 0x4D7C9FC: msWMSDispatch (mapwms.c:4992)
==4245==    by 0x4DBB5D3: msOWSDispatch (mapows.c:244)
==4245==    by 0x4E4669C: msCGIDispatchRequest (mapservutil.c:1607)
==4245==    by 0x401129: main (mapserv.c:259)
==4245== 
==4245== Invalid read of size 4
==4245==    at 0x4E0DF98: msRasterQueryByPoint (maprasterquery.c:1118)
==4245==    by 0x4D3A789: msQueryByPoint (mapquery.c:1608)
==4245==    by 0x4D791C2: msWMSFeatureInfo (mapwms.c:3996)
==4245==    by 0x4D7C9FC: msWMSDispatch (mapwms.c:4992)
==4245==    by 0x4DBB5D3: msOWSDispatch (mapows.c:244)
==4245==    by 0x4E4669C: msCGIDispatchRequest (mapservutil.c:1607)
==4245==    by 0x401129: main (mapserv.c:259)
==4245==  Address 0x96a08fc is 12 bytes inside a block of size 216 free'd
==4245==    at 0x4A072BA: free (vg_replace_malloc.c:446)
==4245==    by 0x4E0B33C: msRasterLayerInfoFree (maprasterquery.c:167)
==4245==    by 0x4E0DB07: msRasterQueryByRect (maprasterquery.c:960)
==4245==    by 0x4E0DF14: msRasterQueryByPoint (maprasterquery.c:1101)
==4245==    by 0x4D3A789: msQueryByPoint (mapquery.c:1608)
==4245==    by 0x4D791C2: msWMSFeatureInfo (mapwms.c:3996)
==4245==    by 0x4D7C9FC: msWMSDispatch (mapwms.c:4992)
==4245==    by 0x4DBB5D3: msOWSDispatch (mapows.c:244)
==4245==    by 0x4E4669C: msCGIDispatchRequest (mapservutil.c:1607)
==4245==    by 0x401129: main (mapserv.c:259)
==4245== 
==4245== Invalid write of size 4
==4245==    at 0x4E0DFA8: msRasterQueryByPoint (maprasterquery.c:1119)
==4245==    by 0x4D3A789: msQueryByPoint (mapquery.c:1608)
==4245==    by 0x4D791C2: msWMSFeatureInfo (mapwms.c:3996)
==4245==    by 0x4D7C9FC: msWMSDispatch (mapwms.c:4992)
==4245==    by 0x4DBB5D3: msOWSDispatch (mapows.c:244)
==4245==    by 0x4E4669C: msCGIDispatchRequest (mapservutil.c:1607)
==4245==    by 0x401129: main (mapserv.c:259)
==4245==  Address 0x96a08fc is 12 bytes inside a block of size 216 free'd
==4245==    at 0x4A072BA: free (vg_replace_malloc.c:446)
==4245==    by 0x4E0B33C: msRasterLayerInfoFree (maprasterquery.c:167)
==4245==    by 0x4E0DB07: msRasterQueryByRect (maprasterquery.c:960)
==4245==    by 0x4E0DF14: msRasterQueryByPoint (maprasterquery.c:1101)
==4245==    by 0x4D3A789: msQueryByPoint (mapquery.c:1608)
==4245==    by 0x4D791C2: msWMSFeatureInfo (mapwms.c:3996)
==4245==    by 0x4D7C9FC: msWMSDispatch (mapwms.c:4992)
==4245==    by 0x4DBB5D3: msOWSDispatch (mapows.c:244)
==4245==    by 0x4E4669C: msCGIDispatchRequest (mapservutil.c:1607)
==4245==    by 0x401129: main (mapserv.c:259)
==4245== 
==4245== Invalid write of size 4
==4245==    at 0x4E0DFF5: msRasterQueryByPoint (maprasterquery.c:1125)
==4245==    by 0x4D3A789: msQueryByPoint (mapquery.c:1608)
==4245==    by 0x4D791C2: msWMSFeatureInfo (mapwms.c:3996)
==4245==    by 0x4D7C9FC: msWMSDispatch (mapwms.c:4992)
==4245==    by 0x4DBB5D3: msOWSDispatch (mapows.c:244)
==4245==    by 0x4E4669C: msCGIDispatchRequest (mapservutil.c:1607)
==4245==    by 0x401129: main (mapserv.c:259)
==4245==  Address 0x96a08fc is 12 bytes inside a block of size 216 free'd
==4245==    at 0x4A072BA: free (vg_replace_malloc.c:446)
==4245==    by 0x4E0B33C: msRasterLayerInfoFree (maprasterquery.c:167)
==4245==    by 0x4E0DB07: msRasterQueryByRect (maprasterquery.c:960)
==4245==    by 0x4E0DF14: msRasterQueryByPoint (maprasterquery.c:1101)
==4245==    by 0x4D3A789: msQueryByPoint (mapquery.c:1608)
==4245==    by 0x4D791C2: msWMSFeatureInfo (mapwms.c:3996)
==4245==    by 0x4D7C9FC: msWMSDispatch (mapwms.c:4992)
==4245==    by 0x4DBB5D3: msOWSDispatch (mapows.c:244)
==4245==    by 0x4E4669C: msCGIDispatchRequest (mapservutil.c:1607)
==4245==    by 0x401129: main (mapserv.c:259)
==4245== 
[Thu Oct  3 16:46:55 2013].418330 msQueryByPoint(): Search returned no results. No matching record(s) found.
Content-Type: application/json

==4245== 
==4245== HEAP SUMMARY:
==4245==     in use at exit: 10,742 bytes in 23 blocks
==4245==   total heap usage: 2,755 allocs, 2,732 frees, 1,012,224 bytes allocated
==4245== 
==4245== LEAK SUMMARY:
==4245==    definitely lost: 152 bytes in 11 blocks
==4245==    indirectly lost: 38 bytes in 2 blocks
==4245==      possibly lost: 0 bytes in 0 blocks
==4245==    still reachable: 10,552 bytes in 10 blocks
==4245==         suppressed: 0 bytes in 0 blocks
==4245== Rerun with --leak-check=full to see details of leaked memory
==4245== 
==4245== For counts of detected and suppressed errors, rerun with: -v
==4245== ERROR SUMMARY: 5 errors from 5 contexts (suppressed: 7 from 7)
```