Allow passing arguments with -- in addition to -.

This allows the Unix-like command-line argument --show.  We keep the
existing -show.

Test: get_rust_pkg.py -show foo
Test: get_rust_pkg.py --show foo
Change-Id: I5906e0c59ef6f9e4ad33b0a9645a1fc4d9d9e1aa
1 file changed