[build-script] add jobs flag

Author: shahmishal

utils/build-script

@@ -970,6 +970,11 @@ def main_preset():
         "--distcc",
         help="use distcc",
         action=arguments.action.optional_bool)
+    parser.add_argument(
+        "-j", "--jobs",
+        help="the number of parallel build jobs to use",
+        type=int,
+        dest="build_jobs")
     parser.add_argument(
         "preset_substitutions_raw",
         help="'name=value' pairs that are substituted in the preset",
@@ -1013,6 +1018,8 @@ def main_preset():
     build_script_args += preset_args
     if args.distcc:
         build_script_args += ["--distcc"]
+    if args.build_jobs:
+        build_script_args += ["--jobs", str(args.build_jobs)]
 
     diagnostics.note(
         "using preset '" + args.preset + "', which expands to \n\n" +