File grepcidr-obey-cflags.patch of Package grepcidr

diff --git a/Makefile b/Makefile
index 61edc86..de103c1 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,7 @@ MANDIR=$(DATAROOTDIR)/man
 INFODIR=$(DATAROOTDIR)/info
 
 CPPFLAGS=
-CFLAGS=-O3 -Wall -Werror
+CFLAGS+=-O3 -Wall -Werror
 LDFLAGS=
 
 all: grepcidr