Install linphone pkgconfig file

--- a/share/CMakeLists.txt
+++ b/share/CMakeLists.txt
@@ -72,4 +72,12 @@
 	)
 endif()
 
+set(prefix ${CMAKE_INSTALL_PREFIX})
+set(exec_prefix ${prefix}/bin)
+set(libdir ${prefix}/lib)
+set(includedir ${prefix}/include)
+
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/linphone.pc.in ${CMAKE_CURRENT_BINARY_DIR}/linphone.pc)
+install(FILES ${CMAKE_CURRENT_BINARY_DIR}/linphone.pc DESTINATION "${CMAKE_INSTALL_LIBDIR}/pkgconfig")
+
 add_subdirectory(rings)
