Spelling: It's Versus Its

Corrects incorrect usage of contraction for 'it is', when possessive 'its' was required.

Differential Revision: https://developer.blender.org/D9250

Reviewed by Campbell Barton

intern/mikktspace/mikktspace.c

@@ -1076,7 +1076,7 @@ static tbool AssignRecur(const int piTriListIn[],
     return TFALSE;
   if ((pMyTriInfo->iFlag & GROUP_WITH_ANY) != 0) {
     // first to group with a group-with-anything triangle
-    // determines it's orientation.
+    // determines its orientation.
     // This is the only existing order dependency in the code!!
     if (pMyTriInfo->AssignedGroup[0] == NULL && pMyTriInfo->AssignedGroup[1] == NULL &&
         pMyTriInfo->AssignedGroup[2] == NULL) {