fix(rpm): propagate main() return code as process exit code (#1024)

Wrap the main() call with sys.exit() so that non-zero return values
from main() are properly reflected in the process exit code.

pkg/make_rpm.py

diff --git a/pkg/make_rpm.py b/pkg/make_rpm.py
index 7b44ed5..d4a7c37 100644
--- a/pkg/make_rpm.py
+++ b/pkg/make_rpm.py
@@ -622,6 +622,6 @@
 
 
 if __name__ == '__main__':
-  main(sys.argv[1:])
+  sys.exit(main(sys.argv[1:]))
 
 # vim: ts=2:sw=2: