gxvmort2.c: Fix C4018: '>': signed/unsigned mismatch

freetype\src\gxvalid\gxvmort2.c(195,30): warning C4018: '>': signed/unsigned mismatch

Authored By: botder (at 4dcf140#diff-a3a76e7f82c9632f3db0ce08b8b70c2f0938ab3219894f988b0b069a3f7e0c6a)

Before upstream receives it, keep picking this commit on every Freetype update.

Author: Dutchman101

vendor/freetype/src/gxvalid/gxvmort2.c

@@ -192,8 +192,8 @@
                      offset, optdata->ligatureTable - offset * 2 ));
 
         GXV_SET_ERR_IF_PARANOID( FT_INVALID_OFFSET );
-      } else if ( offset * 2 >
-                  optdata->ligatureTable + optdata->ligatureTable_length )
+      } else if ( offset * 2u >
+                  (FT_ULong)( optdata->ligatureTable + optdata->ligatureTable_length ) )
       {
         GXV_TRACE(( "too long offset 0x%08lx:"
                     " 2 x offset > ligatureTable + ligatureTable_length"