Let build tool handle default --jobs

src/fprime/fbuild/cli.py

@@ -143,9 +143,8 @@ def add_target_parser(
         parser.add_argument(
             "-j",
             "--jobs",
-            default=1,
             type=int,
-            help="Parallel build job count. Default: %(default)s.",
+            help="Parallel build job count. Default: build tool default (make: 1, ninja: # of cores)",
         )
     parser, flags = existing[target.mnemonic]
     new_flags = [flag for flag in target.flags if flag not in flags]

src/fprime/util/cli.py

@@ -242,7 +242,8 @@ def validate(parsed, unknown):
     # Build type only for generate, jobs only for non-generate
     elif parsed.command in [target.mnemonic for target in Target.get_all_targets()]:
         parsed.settings = None  # Force to load from cache if possible
-        make_args["--jobs"] = 1 if parsed.jobs <= 0 else parsed.jobs
+        if parsed.jobs:
+            make_args["--jobs"] = 1 if parsed.jobs <= 0 else parsed.jobs
     # Check if any arguments are still unknown
     if unknown:
         runnable = f"{os.path.basename(sys.argv[0])} {parsed.command}"