More GC fixes. Most notably, mark the thread object as not collectable, since it's hidden away in TLS where the GC can't find it.

GC now works well enough for LanguageKit to run.



git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@33123 72102866-910b-0410-8b05-ffd578937521

Source/GSString.m

@@ -477,7 +477,7 @@ fixBOM(unsigned char **bytes, NSUInteger*length, BOOL *owned,
        */
       if (original == bytes)
 	{
-#if	GS_WITH_GC || __OBJC_GC__
+#if	GS_WITH_GC
 	  chars = NSAllocateCollectable(length, 0);
 #else
 	  chars = NSZoneMalloc([self zone], length);