Support pkg-config

Thanks for the PR.
xtensor-stack/xtensor#338

Author: yssource

CMakeLists.txt

@@ -121,3 +121,10 @@ set(CMAKE_SIZEOF_VOID_P ${_XFRAME_CMAKE_SIZEOF_VOID_P})
 install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake
               ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake
         DESTINATION ${XFRAME_CMAKECONFIG_INSTALL_DIR})
+
+
+configure_file(${PROJECT_NAME}.pc.in
+        "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}.pc"
+        @ONLY)
+install(FILES "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}.pc"
+        DESTINATION "${CMAKE_INSTALL_LIBDIR}/pkgconfig/")

xframe.pc.in

@@ -0,0 +1,8 @@
+prefix=@CMAKE_INSTALL_PREFIX@
+libdir=${prefix}/@CMAKE_INSTALL_LIBDIR@
+includedir=${prefix}/include
+
+Name: xframe
+Description: xframe is a C++ library meant for numerical analysis with Multi-dimensional labeled arrays and data frame based on xtensor.
+Version: @xframe_VERSION@
+Cflags: -I${includedir}