Fix libgc compilation with clang.

diff --git a/libgc/pthread_support.c b/libgc/pthread_support.c
index bc31c9733a7d40e77e2c7ed3156516401901d576..ccafb3b1169e96fa6847a794ea4b01d1421ba8b1 100644 (file)
--- a/libgc/pthread_support.c
+++ b/libgc/pthread_support.c
@@ -66,6 +66,7 @@
     --> Macro replaced by USE_COMPILER_TLS
 # endif
 
+#ifndef USE_COMPILER_TLS
 # if (defined(GC_DGUX386_THREADS) || defined(GC_OSF1_THREADS) || \
       defined(GC_DARWIN_THREADS) || defined(GC_AIX_THREADS)) || \
       defined(GC_NETBSD_THREADS) && !defined(USE_PTHREAD_SPECIFIC) || \
@@ -73,6 +74,7 @@
       defined(GC_OPENBSD_THREADS)
 #   define USE_PTHREAD_SPECIFIC
 # endif
+#endif
 
 # if defined(GC_DGUX386_THREADS) && !defined(_POSIX4A_DRAFT10_SOURCE)
 #   define _POSIX4A_DRAFT10_SOURCE 1