libs/libstrophe: install pkg-config .pc file

This helps packages depending on libs/libstrophe in finding the library via pkg-config or CMake's PKG_SEARCH_MODULE

Signed-off-by: Enrico Mioso <mrkiko.rs@gmail.com>

libs/libstrophe/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=libstrophe
 PKG_VERSION:=0.9.2
-PKG_RELEASE=1
+PKG_RELEASE=2
 
 PKG_LICENSE:=GPL-3.0
 PKG_LICENSE_FILES:=COPYING
@@ -56,7 +56,11 @@ define Build/InstallDev
 	$(CP) $(PKG_INSTALL_DIR)/usr/include/ $(1)/usr/
 
 	$(INSTALL_DIR) $(1)/usr/lib/
+	$(INSTALL_DIR) $(1)/usr/lib/pkgconfig
 	$(CP) $(PKG_INSTALL_DIR)/usr/lib/libstrophe.{la,a,so*} $(1)/usr/lib/
+	$(CP) \
+		$(PKG_INSTALL_DIR)/usr/lib/pkgconfig/libstrophe.pc \
+		$(1)/usr/lib/pkgconfig/
 endef
 
 define Package/libstrophe/install