honor CFLAGS

Index: Makefile
--- Makefile.orig
+++ Makefile
@@ -5,7 +5,7 @@ C_OBJECTS   = $(patsubst $(SOURCE_DIR)/%.c, $(BUILD_DI
 
 OBJECTS = $(C_OBJECTS)
 # Flags passed to the C compiler
-CFLAGS  = -pipe -fno-math-errno -Werror -Wno-error=missing-braces -Wno-error=strict-aliasing
+CFLAGS  += -fno-math-errno -Werror -Wno-error=missing-braces -Wno-error=strict-aliasing
 # Flags passed to the linker
 LDFLAGS = -g -rdynamic
 # Name of the main executable
