spearmint: Fix range check in CL_UpdateVisiblePings_f

Allow AS_GLOBAL to be used again. I changed the order of the values.

Found by Coverity.
spearmint: GL2, add missing break (non-issue atm)

The missing break caused RB_SurfaceAxis to run, but it's stubbed and does nothing.

Found by Coverity.
spearmint: Fix handling shaders with 10 nested ifs

Spearmint has support for using 'if' and 'endif' in shaders.
There is a limited of 10 nested ifs, which was not properly limited
and would cause a buffer overflow if there are 11 nested ifs.

Found by Coverity.
spearmint: Make FS_Seek return 0 for success on zipped files

fseek returns 0 on success and non-zero on failure. Do the same
with zipped files.
spearmint: FS_Seek returns non-zero on failure, so don't do "< 0"

References online say fseek returns non-zero, not negative.
spearmint: Handle FS_Seek error in CL_ValidDemoFile

Coverity warned about it. There are many other unhandled cases, but this one is mine.
Fix potential out of bounds access caused by CM_GridPlane

Coverity doesn't care if there is a warning, out of bounds access is bad.
Don't use memset with non-zero value to fill ints

Coverity reported using value -2 as a bad memset. Really doesn't make sense when filling ints and not bytes too.
Fix potential buffer overflow in PS_ReadPrimitive

Found by Coverity.
spearmint: Fix possible out of bounds by bad voip packet

Found by Coverity.
Fix unchecked buffer size issues in l_script.c and l_precomp.c

Found by Coverity.
Fix max bans range check in SV_AddBanToList

Adding too many bans would write out of bounds. Found by Coverity.
Have OpenGL2 "map $lightmap" check for NULL tr.lightmaps too

Zero length lightmap lump will have NULL tr.lightmaps.

OpenGL1 already has this check, because r_vertexLight 1
would crash Team Arena. OpenGL2 does not disable loading lightmaps
when r_vertexLight is 1 though, so it does not have that issue.
Fix potential buffer overflow caused by long tcMod args

Found by Coverity.
Merge remote-tracking branch 'ioquake3/master'