grpc: correct absl pkgconfig sed-hack

srcpkgs/grpc/template

@@ -1,7 +1,7 @@
 # Template file for 'grpc'
 pkgname=grpc
 version=1.39.1
-revision=2
+revision=3
 _abseilver=997aaf3a28308eba1b9156aa35ab7bca9688e9f6
 build_style=cmake
 configure_args="-DBUILD_SHARED_LIBS=ON
@@ -45,17 +45,17 @@ post_patch() {
 post_build() {
 	# Clean up unneeded absl linker arguments from pkgconfig files
 	sed -e 's/-labsl_[^[:space:]]\+[[:space:]]*//g' \
-		-i build/libs/opt/pkgconfig/*.pc
-
-	# Add custom absl include root to grpcpp cflags
-	sed -e 's,^Cflags:.*,& -I${includedir}/grpc_absl,' \
-		-i build/libs/opt/pkgconfig/grpc++*.pc
+		-i build/lib/pkgconfig/*.pc
 }
 
 post_install() {
 	# Remove unnecessary absl static libs and cmake modules
 	rm "${DESTDIR}"/usr/lib/libabsl*.a
 	rm -rf "${DESTDIR}/usr/lib/cmake/absl"
+	
+	# Add custom absl include root to grpcpp cflags
+	vsed -e 's,^Cflags:.*,& -I${includedir}/grpc_absl,' \
+		-i ${DESTDIR}/usr/lib/pkgconfig/grpc++*.pc
 }
 
 grpc-devel_package() {