fix upstream Makefile

--- wiringPi-0.1.orig/devLib/Makefile	2014-12-05 14:48:57.000000000 +0100
+++ wiringPi-0.1/devLib/Makefile	2014-12-05 15:35:35.470864970 +0100
@@ -32,9 +32,9 @@ DYNAMIC=libwiringPiDev.so.$(VERSION)
 
 #DEBUG	= -g -O0
 DEBUG	= -O2
-CC	= gcc
+CC	?= gcc
 INCLUDE	= -I.
-CFLAGS	= $(DEBUG) -Wformat=2 -Wall $(INCLUDE) -Winline -pipe -fPIC
+CFLAGS	?= -Wformat=2 -Wall $(INCLUDE) -Winline -pipe -fPIC
 
 LIBS    =
 
@@ -59,11 +59,11 @@ $(STATIC):	$(OBJ)
 
 $(DYNAMIC):	$(OBJ)
 	@echo "[Link (Dynamic)]"
-	@$(CC) -shared -Wl,-soname,libwiringPiDev.so -o libwiringPiDev.so.$(VERSION) -lpthread $(OBJ)
+	$(CC) -shared -Wl,-soname,libwiringPiDev.so -o libwiringPiDev.so.$(VERSION) -lpthread $(OBJ)
 
 .c.o:
 	@echo [Compile] $<
-	@$(CC) -c $(CFLAGS) $< -o $@
+	$(CC) -c $(CPPFLAGS) $(CFLAGS) $< -o $@
 
 .PHONY:	clean
 clean: