Merge pull request #2159 from martin-frbg/issue2149

Avoid unintentional activation of TLS codepath via USE_TLS=0

Author: martin-frbg

Makefile.system

@@ -1070,7 +1070,7 @@ ifdef USE_SIMPLE_THREADED_LEVEL3
 CCOMMON_OPT	+= -DUSE_SIMPLE_THREADED_LEVEL3
 endif
 
-ifdef USE_TLS
+ifeq ($(USE_TLS), 1)
 CCOMMON_OPT += -DUSE_TLS
 endif