enable -fno-strict-aliasing for clang (#156)

Type punning via unions in clang is not safe without -fno-strict-aliasing. See https://bugs.llvm.org//show_bug.cgi?id=31928.

Make.inc

@@ -39,7 +39,7 @@ AR = ar
 ifeq ($(USECLANG),1)
 USEGCC = 0
 CC = clang
-CFLAGS_add += -fno-builtin
+CFLAGS_add += -fno-builtin -fno-strict-aliasing
 endif
 
 ifeq ($(USEGCC),1)