Linux: disabled alfont_get_string function

alfont_get_string is a part of alfont 2.* library. It's current implementation uses malloc_usable_size function that is non-standard and may cause linking issues under some circumstances.
Since this particular function is not used anywhere in the engine, it is safer to remove it from compilation for now.

Engine/libsrc/alfont-2.0.9/alfont.c

@@ -21,20 +21,12 @@
 #include <iconv.h>
 #else			//run in Other
 #include <locale.h>
-#include <malloc.h>
 #include <wchar.h>
 #endif
 
 #include FT_FREETYPE_H
 #include FT_GLYPH_H
 
-#define _msize malloc_usable_size
-
-#ifdef IOS_VERSION
-// Defined in libc.c as a stub method
-size_t malloc_usable_size (void *ptr);
-#endif
-
 /* structs */
 
 struct ALFONT_FONT {
@@ -4259,6 +4251,12 @@ int alfont_ugetxc(ALFONT_FONT *f, const char **s) {
   return character;
 }
 
+// Following function alfont_get_string is removed from compilation because it 
+// is implemented with the use of non-standart malloc_usable_size function
+// (defined as _msize). This may cause linking errors on some Linux systems or
+// if using particular compilers.
+#if 0
+
 void alfont_get_string(ALFONT_FONT *f, const char *s , char **out){
   char *lpszW;
   char *lpszW_pointer=NULL; //used for freeing string
@@ -4509,6 +4507,8 @@ void alfont_get_string(ALFONT_FONT *f, const char *s , char **out){
   }
 }
 
+#endif // DISABLED
+
 int alfont_need_uconvert(ALFONT_FONT *f, const char *str) {
   char *lpszW;
   char *str_pointer=NULL; //used for original string fixed by autofix