zathura-cb: fix CFLAGS and LDFLAGS

srcpkgs/zathura-cb/template

@@ -1,7 +1,7 @@
 # Template file for 'zathura-cb'
 pkgname=zathura-cb
 version=0.1.4
-revision=2
+revision=3
 build_style=gnu-makefile
 maintainer="Dominik Honnef <dominik@honnef.co>"
 hostmakedepends="pkg-config"
@@ -12,6 +12,11 @@ short_desc="Comic book support for zathura"
 distfiles="http://pwmt.org/projects/${pkgname}/download/${pkgname}-${version}.tar.gz"
 checksum=f21cb140cce02b3ef8b23eff479a7f66285667ab47cdc099c10cd62eaf239626
 
+pre_build() {
+	sed -i 's/^\(CFLAGS *+=\)/override \1/' config.mk
+	sed -i 's/^\(LDFLAGS *+=\)/override \1/' config.mk
+}
+
 post_install() {
 	vlicense LICENSE
 }