net/mosquitto: install pkg-config files

Install the .pc files to staging directory to help other packages
to find the libraries.

Since the build does not use CMake, we need to manually install the
files and replace two variables using sed.

Filed upstream as https://github.com/eclipse/mosquitto/pull/950

Signed-off-by: Michael Heimpold <michael.heimpold@i2se.com>
Tested-by: Karl Palsson <karlp@etactica.com>

net/mosquitto/Makefile

@@ -197,6 +197,15 @@ define Build/InstallDev
 	$(CP) $(PKG_BUILD_DIR)/lib/cpp/libmosquittopp.so.1 $(1)/usr/lib/
 	$(LN) libmosquitto.so.1 $(1)/usr/lib/libmosquitto.so
 	$(LN) libmosquittopp.so.1 $(1)/usr/lib/libmosquittopp.so
+	$(INSTALL_DIR) $(1)/usr/lib/pkgconfig
+	$(CP) $(PKG_BUILD_DIR)/libmosquitto.pc.in $(1)/usr/lib/pkgconfig/libmosquitto.pc
+	sed -i -e "s#@CMAKE_INSTALL_PREFIX@#/usr#" \
+	       -e "s#@VERSION@#$(PKG_VERSION)#" \
+	    $(1)/usr/lib/pkgconfig/libmosquitto.pc
+	$(CP) $(PKG_BUILD_DIR)/libmosquittopp.pc.in $(1)/usr/lib/pkgconfig/libmosquittopp.pc
+	sed -i -e "s#@CMAKE_INSTALL_PREFIX@#/usr#" \
+	       -e "s#@VERSION@#$(PKG_VERSION)#" \
+	    $(1)/usr/lib/pkgconfig/libmosquittopp.pc
 endef
 
 # This installs files on the target.  Compare with Build/InstallDev