Remove dependency to posix-extension function

include/assimp/StringComparison.h

@@ -145,11 +145,7 @@ int ASSIMP_stricmp(const char *s1, const char *s2) {
 #if (defined _MSC_VER)
 
     return ::_stricmp(s1, s2);
-#elif defined(__GNUC__)
-
-    return ::strcasecmp(s1, s2);
 #else
-
     char c1, c2;
     do {
         c1 = tolower(*s1++);