Do not hardcode libdir and includedir in pkg config files

CMakeLists.txt

@@ -234,6 +234,8 @@ add_custom_target(spirv-tools-pkg-config ALL
                       -DTEMPLATE_FILE=${CMAKE_CURRENT_SOURCE_DIR}/cmake/SPIRV-Tools.pc.in
                       -DOUT_FILE=${CMAKE_CURRENT_BINARY_DIR}/SPIRV-Tools.pc
                       -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
+                      -DCMAKE_INSTALL_LIBDIR=${CMAKE_INSTALL_LIBDIR}
+                      -DCMAKE_INSTALL_INCLUDEDIR=${CMAKE_INSTALL_INCLUDEDIR}
                       -DSPIRV_LIBRARIES=${SPIRV_LIBRARIES}
                       -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/write_pkg_config.cmake
         DEPENDS "CHANGES" "cmake/SPIRV-Tools.pc.in" "cmake/write_pkg_config.cmake")
@@ -242,6 +244,8 @@ add_custom_target(spirv-tools-shared-pkg-config ALL
                       -DTEMPLATE_FILE=${CMAKE_CURRENT_SOURCE_DIR}/cmake/SPIRV-Tools-shared.pc.in
                       -DOUT_FILE=${CMAKE_CURRENT_BINARY_DIR}/SPIRV-Tools-shared.pc
                       -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
+                      -DCMAKE_INSTALL_LIBDIR=${CMAKE_INSTALL_LIBDIR}
+                      -DCMAKE_INSTALL_INCLUDEDIR=${CMAKE_INSTALL_INCLUDEDIR}
                       -DSPIRV_SHARED_LIBRARIES=${SPIRV_SHARED_LIBRARIES}
                       -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/write_pkg_config.cmake
         DEPENDS "CHANGES" "cmake/SPIRV-Tools-shared.pc.in" "cmake/write_pkg_config.cmake")

cmake/SPIRV-Tools-shared.pc.in

@@ -1,7 +1,7 @@
 prefix=@CMAKE_INSTALL_PREFIX@
 exec_prefix=${prefix}
-libdir=${prefix}/lib64
-includedir=${prefix}/include
+libdir=${prefix}/@CMAKE_INSTALL_LIBDIR@
+includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
 
 Name: SPIRV-Tools
 Description: Tools for SPIR-V

cmake/SPIRV-Tools.pc.in

@@ -1,7 +1,7 @@
 prefix=@CMAKE_INSTALL_PREFIX@
 exec_prefix=${prefix}
-libdir=${prefix}/lib64
-includedir=${prefix}/include
+libdir=${prefix}/@CMAKE_INSTALL_LIBDIR@
+includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
 
 Name: SPIRV-Tools
 Description: Tools for SPIR-V