Remove -ansi flag for Clang

It seems this flag is only for gcc and
yields a warning under OSX Mavericks:

clang: warning: argument unused during compilation: '-ansi'

No functional change.

src/Makefile

@@ -175,7 +175,7 @@ endif
 ifeq ($(COMP),clang)
 	comp=clang
 	CXX=clang++
-	CXXFLAGS += -ansi -pedantic -Wno-long-long -Wextra -Wshadow
+	CXXFLAGS += -pedantic -Wno-long-long -Wextra -Wshadow
 endif
 
 ifeq ($(comp),icc)