Should we map libraries specified on the command line to the current variant? `-lgl` to the required variant

 If user specifies `-lc` on the command line should we map that to `-lc-mt` to according to the variant naming scheme in `tools/system_libraries.py`.   I tend to think that we should.  

This will allow things like `-GL` to map to `libGL-mt-emu.a` automatically. 