gcc: fix gcc 4.8 build when thread support is disabled

When thread support is disabled, the libitm and libatomic libraries
from gcc should be disabled, otherwise, the build of gcc fails.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

toolchain/gcc/gcc-uclibc-4.x.mk

@@ -203,7 +203,7 @@ GCC_TLS:=--disable-tls
 endif
 
 ifeq ($(BR2_PTHREADS_NONE),y)
-THREADS:=--disable-threads
+THREADS:=--disable-threads --disable-libitm --disable-libatomic
 else
 THREADS:=--enable-threads
 endif