Use CPPFLAGS for settings that belong the C Preprocessor. Ports should be able to set CFLAGS without breaking the build

Makefile.bsd

@@ -18,11 +18,11 @@ debug: entr_spec
 	gdb -q entr_spec
 
 entr: entr.c ${EXTRA_SRC}
-	${CC} ${CPPFLAGS} ${CFLAGS} ${EXTRA_SRC} entr.c -o $@ ${LDFLAGS}
+	${CC} ${CFLAGS} ${CPPFLAGS} ${EXTRA_SRC} entr.c -o $@ ${LDFLAGS}
 	@chmod +x $@
 
 entr_spec: entr_spec.c entr.c ${EXTRA_SRC}
-	${CC} ${CPPFLAGS} ${CFLAGS} ${EXTRA_SRC} entr_spec.c -o $@ ${LDFLAGS}
+	${CC} ${CFLAGS} ${CPPFLAGS} ${EXTRA_SRC} entr_spec.c -o $@ ${LDFLAGS}
 	@chmod +x $@
 
 clean:

Makefile.linux

@@ -1,4 +1,4 @@
-CFLAGS += -D_GNU_SOURCE -D_LINUX_PORT -Imissing
+CPPFLAGS += -D_GNU_SOURCE -D_LINUX_PORT -Imissing
 MANPREFIX ?= ${PREFIX}/share/man
 EXTRA_SRC = missing/strlcpy.c missing/kqueue_inotify.c
 

Makefile.macos

@@ -1,4 +1,4 @@
-CFLAGS += -D_MACOS_PORT
+CPPFLAGS += -D_MACOS_PORT
 MANPREFIX ?= ${PREFIX}/share/man
 EXTRA_SRC = missing/fmemopen.c