Revert "Minor"

This reverts commit 0a492357.

Enables code on more compilers.

src/hb-warning.cc

@@ -29,11 +29,38 @@
 
 
 #if defined(HB_ATOMIC_INT_NIL)
-#pragma message("Could not find any system to define atomic_int macros, library may NOT be thread-safe.")
+#ifdef _MSC_VER
+#pragma message("Could not find any system to define atomic_int macros, library may NOT be thread-safe")
+#else
+#warning "Could not find any system to define atomic_int macros, library may NOT be thread-safe"
 #endif
+#endif
+
 #if defined(HB_MUTEX_IMPL_NIL)
-#pragma message("Could not find any system to define mutex macros, library may NOT be thread-safe.")
+#ifdef _MSC_VER
+#pragma message("Could not find any system to define mutex macros, library may NOT be thread-safe")
+#else
+#warning "Could not find any system to define mutex macros, library may NOT be thread-safe"
+#endif
 #endif
+
 #if defined(HB_ATOMIC_INT_NIL) || defined(HB_MUTEX_IMPL_NIL)
-#pragma message("To suppress these warnings, define HB_NO_MT.")
+#ifdef _MSC_VER
+#pragma message("To suppress these warnings, define HB_NO_MT")
+#else
+#warning "To suppress these warnings, define HB_NO_MT"
+#endif
+#endif
+
+
+#include "hb-unicode-private.hh"
+
+#if !defined(HB_NO_UNICODE_FUNCS) && defined(HB_UNICODE_FUNCS_NIL)
+#ifdef _MSC_VER
+#pragma message("Could not find any Unicode functions implementation, you have to provide your own")
+#pragma message("To suppress this warnings, define HB_NO_UNICODE_FUNCS")
+#else
+#warning "Could not find any Unicode functions implementation, you have to provide your own"
+#warning "To suppress this warning, define HB_NO_UNICODE_FUNCS"
+#endif
 #endif