Install pkgconfig files

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -609,6 +609,13 @@
 	add_subdirectory(tools)
 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}/mediastreamer.pc.in ${CMAKE_CURRENT_BINARY_DIR}/mediastreamer.pc)
+install(FILES ${CMAKE_CURRENT_BINARY_DIR}/mediastreamer.pc DESTINATION "${CMAKE_INSTALL_LIBDIR}/pkgconfig")
 
 include(CMakePackageConfigHelpers)
 write_basic_package_version_file(
