wavpack: add exec_prefix to wavpack.pc

srcpkgs/wavpack/template

@@ -1,7 +1,7 @@
 # Template file for 'wavpack'
 pkgname=wavpack
 version=4.70.0
-revision=2
+revision=3
 build_style=gnu-configure
 short_desc="An audio codec (lossy and lossless)"
 homepage="http://www.wavpack.com/"
@@ -14,6 +14,10 @@ if [ "$XBPS_TARGET_MACHINE" = "i686" -o "$XBPS_TARGET_MACHINE" = "x86_64" ]; the
 	configure_args="--enable-mmx"
 fi
 
+pre_configure() {
+	sed -i 's/^prefix=.*/&\nexec_&/' wavpack.pc.in
+}
+
 libwavpack_package() {
 	short_desc+=" - shared library"
 	pkg_install() {