Threads: add enable threading flag correctly

Author: Kiran Pamnany

Make.inc

@@ -280,7 +280,6 @@ endif
 ifeq ($(JULIA_THREADS), 1)
 LLVM_VER := svn
 LLVM_GIT_URL_LLVM := https://github.com/JuliaLang/llvm.git -b jn/tls37
-JULIA_ENABLE_THREADING := 1
 endif
 
 # Compiler specific stuff
@@ -846,6 +845,12 @@ JCPPFLAGS += -D_WIN32_WINNT=0x0502
 UNTRUSTED_SYSTEM_LIBM := 1
 endif
 
+# Threads
+ifeq ($(JULIA_THREADS), 1)
+JCFLAGS += -DJULIA_ENABLE_THREADING
+JCXXFLAGS += -DJULIA_ENABLE_THREADING
+endif
+
 # Intel VTune Amplifier
 ifeq ($(USE_INTEL_JITEVENTS), 1)
 JCPPFLAGS += -DJL_USE_INTEL_JITEVENTS