cmake: Use parallel builds for protobuf.

Author: rsomla1

cdk/cmake/DepFindProtobuf.cmake

@@ -221,9 +221,20 @@ if(SUNPRO)
   )
 endif()
 
+#
+# Try using parallel builds for protobuf.
+#
+
+set(opt_build)
+set(opt_tool)
+if(NOT CMAKE_VERSION VERSION_LESS 3.12)
+  set(opt_build --parallel)
+elseif(CMAKE_MAKE_PROGRAM MATCHES "make")
+  set(opt_tool -j)
+endif()
 
 add_custom_command(OUTPUT "${build_stamp}"
-  COMMAND ${CMAKE_COMMAND} --build . --config ${CONFIG_EXPR}
+  COMMAND ${CMAKE_COMMAND} --build . ${opt_build} --config ${CONFIG_EXPR} -- ${opt_tool}
   COMMAND ${CMAKE_COMMAND} -E touch "${build_stamp}"
   WORKING_DIRECTORY "${PB_BINARY_DIR}"
   COMMENT "Building protobuf"