mconf: Don't print a recommendation to use 'make' if CMake build system is in use

Also add some cmake dependencies to rebuild mconf if its source files change.

tools/cmake/kconfig.cmake

@@ -38,7 +38,7 @@ if(NOT MCONF)
     #
     set(MCONF kconfig_bin/mconf)
 
-    externalproject_add(mconf
+    Externalproject_Add(mconf
         SOURCE_DIR ${IDF_PATH}/tools/kconfig
         CONFIGURE_COMMAND ""
         BINARY_DIR "kconfig_bin"
@@ -47,7 +47,16 @@ if(NOT MCONF)
         INSTALL_COMMAND ""
         EXCLUDE_FROM_ALL 1
         )
+
+    file(GLOB mconf_srcfiles ${IDF_PATH}/tools/kconfig/*.c)
+    ExternalProject_Add_StepDependencies(mconf build
+        ${mconf_srcfiles}
+        ${IDF_PATH}/tools/kconfig/Makefile
+        ${CMAKE_CURRENT_LIST_FILE})
+    unset(mconf_srcfiles)
+
     set(menuconfig_depends DEPENDS mconf)
+
 endif()
 
 # Find all Kconfig files for all components

tools/kconfig/mconf.c

@@ -980,11 +980,17 @@ static int handle_exit(void)
 		}
 		/* fall through */
 	case -1:
-		if (!silent)
+		if (!silent) {
+			const char *is_cmake = getenv("IDF_CMAKE");
+			const char *build_msg;
+			if (is_cmake && is_cmake[0] == 'y')
+				build_msg = _("Ready to use CMake (or 'idf.py build') to build the project.");
+			else
+				build_msg = _("Execute 'make' to start the build or try 'make help'.");
 			printf(_("\n\n"
-				 "*** End of the configuration.\n"
+					 "*** End of the configuration.\n"
-				 "*** Execute 'make' to start the build or try 'make help'."
+					 "*** %s\n\n"), build_msg);
-				 "\n\n"));
+		}
 		res = 0;
 		break;
 	default: