Merge pull request #54 from Microsoft/cherry-pick-8c8534e

Wrap some headers in extern "C" for C++ compatibility

objc/encoding.h

@@ -5,6 +5,10 @@
 #ifndef __LIBOBJC_ENCODING_H_INCLUDED__
 #define __LIBOBJC_ENCODING_H_INCLUDED__
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 const char *objc_skip_type_qualifiers (const char *type);
 
 const char *objc_skip_typespec(const char *type);
@@ -71,4 +75,8 @@ void objc_layout_structure_get_info (struct objc_struct_layout *layout,
 #define _F_ONEWAY      0x10
 #define _F_GCINVISIBLE 0x20
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif // __LIBOBJC_ENCODING_H_INCLUDED__

objc/hooks.h

@@ -2,6 +2,10 @@
 #pragma clang system_header
 #endif
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * This file includes all of the hooks that can be used to alter the behaviour
  * of the runtime.  
@@ -102,4 +106,6 @@ typedef IMP (*objc_tracing_hook)(id, SEL, IMP, int, void*);
  */
 int objc_registerTracingHook(SEL, objc_tracing_hook);
 
-
+#ifdef __cplusplus
+}
+#endif

objc/objc-arc.h

@@ -4,6 +4,11 @@
 
 #ifndef __OBJC_ARC_INCLUDED__
 #define __OBJC_ARC_INCLUDED__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * Autoreleases the argument.  Equivalent to [obj autorelease].
  */
@@ -138,5 +143,10 @@ unsigned long objc_arc_autorelease_count_np(void);
  * this thread.
  */
 unsigned long objc_arc_autorelease_count_for_object_np(id);
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif // __OBJC_ARC_INCLUDED__