update submodule
msOGRFileClose: drop useless OGR mutex that could cause a dead-lock with tileindex (#4869)
Fix blending of semi-opaque pixels in average and bilinear resamplers (#4875)
RFC109: Refactor Application of Runtime Substitutions (#4877)

- Rewrite substitution loops to first check for available VALIDATION
  patterns before looping through KVP pairs. This is possible because
  VALIDATIONs are mandatory, and speeds things up substantially in the
  general case when there are few/no substitutions to apply

- Allow runtime substitutions to apply to map->metadata,
  layer->metadata, and all outputformat->formatoptions
Restore lexer file pointer on INCLUDE error (#4871)
Switch off ogr-output streaming mode for non default io contexts (#4858)
Merge branch 'branch-6-4'

Conflicts:
	mapio.h
	maplexer.c
	mapresample.c
	msautotest
update submodule
update submodule after 6.4 merge
add missing map reference to image

When msCreateLegendIcon and msDrawLegendIcon are called from mapscript directly, the image does not have a map assigned. This causes a crash when the legend references a symbol as in the maprendering.c getTile function and tries to get the font from the image's map fontset reference.
add forgotten class substitutions of rfc019 (#4877)
update submodule for #4877 class tests
RFC109: fix inifinite loop on metadata substitutions (#4877)
avoid numerous error messages for failed runtime substitutions (#4877)

don't print error messages in regex/validation checks, the higher level
callers already print one out. also add back debugging messages in the
debug logs.
update submodule
WFS 2.0: generate correct MetadataURL element, and add optional wfs_metadataurl_about layer metadata item (#4886)
UTFGRID: implement escaping of item and data values
Fixing a large number of programming errors found by static analysis

issues found by the coverity scanner, most are memory leaks on error
conditions.
Merge branch 'branch-6-4' into master-coverity

Conflicts:
	mapagg.cpp
	mapcontext.c
	mapdraw.c
	mapfile.c
	mapgd.c
	mapgml.c
	maplabel.c
	maplegend.c
	mapogcfilter.c
	mapoutput.c
	mappostgis.c
	maprendering.c
	mapwfs.c
	mapwfs11.c
	msautotest
fixups after coverity merge