Drop -Werror from reach Makefile

Author: TaoBi22

src/reach/Makefile

@@ -1,6 +1,6 @@
 include ../makefile.include
 
-CFLAGS += -fPIC -Werror -Wreturn-type -Wunknown-pragmas -Wunused-value -Wunused-label
+CFLAGS += -fPIC -Wreturn-type -Wunknown-pragmas -Wunused-value -Wunused-label
 
 ifeq ($(STATIC_REA), 1)
   CXX += -static-libstdc++ -static-libgcc -static