Tweak GC check, make sure GC_init() is called even when ObjC code isn't using GC (stuff internal to the runtime may be)

abi_version.c

@@ -61,7 +61,7 @@ static int known_abi_count =
 	}\
 } while(0)
 
-PRIVATE enum objc_gc_mode current_gc_mode = GC_Optional;
+static enum objc_gc_mode current_gc_mode = GC_Optional;
 
 static BOOL endsWith(const char *string, const char *suffix)
 {

gc_boehm.c

@@ -511,7 +511,6 @@ static void runFinalizers(void)
 
 static void init(void)
 {
-	GC_INIT();
 	char *sigNumber;
 	// Dump GC stats on exit - uncomment when debugging.
 	if (getenv("LIBOBJC_DUMP_GC_STATUS_ON_EXIT"))
@@ -532,7 +531,7 @@ static void init(void)
 
 BOOL objc_collecting_enabled(void)
 {
-	return current_gc_mode != GC_None;
+	return isGCEnabled;
 }
 
 void objc_startCollectorThread(void)
@@ -580,6 +579,7 @@ PRIVATE struct gc_ops gc_ops_boehm =
 
 PRIVATE void enableGC(BOOL exclude)
 {
+	isGCEnabled = YES;
 	if (__sync_bool_compare_and_swap(&gc, &gc_ops_none, &gc_ops_boehm))
 	{
 		gc->init();

gc_ops.h

@@ -54,7 +54,7 @@ enum objc_gc_mode
 /**
  * The current Objective-C garbage collection mode.
  */
-extern enum objc_gc_mode current_gc_mode;
+extern BOOL isGCEnabled;
 
 /**
  * The current set of garbage collector operations to use.

loader.c

@@ -4,6 +4,9 @@
 #include "lock.h"
 #include "loader.h"
 #include "visibility.h"
+#ifdef ENABLE_GC
+#include <gc/gc.h>
+#endif
 
 /**
  * Runtime lock.  This is exposed in 
@@ -32,6 +35,9 @@ void __objc_exec_class(struct objc_module_abi_8 *module)
 
 	if (first_run)
 	{
+#if ENABLE_GC
+		GC_INIT();
+#endif
 		// Create the main runtime lock.  This is not safe in theory, but in
 		// practice the first time that this function is called will be in the
 		// loader, from the main thread.  Future loaders may run concurrently,

properties.m

@@ -20,7 +20,7 @@ id objc_getProperty(id obj, SEL _cmd, ptrdiff_t offset, BOOL isAtomic)
 	if (nil == obj) { return nil; }
 	char *addr = (char*)obj;
 	addr += offset;
-	if (current_gc_mode == GC_Required)
+	if (isGCEnabled)
 	{
 		return *(id*)addr;
 	}
@@ -47,7 +47,7 @@ void objc_setProperty(id obj, SEL _cmd, ptrdiff_t offset, id arg, BOOL isAtomic,
 	char *addr = (char*)obj;
 	addr += offset;
 
-	if (current_gc_mode == GC_Required)
+	if (isGCEnabled)
 	{
 		if (isCopy)
 		{