Fix for GAS treating -m32r as -m32rx

[Doug Evans]

Nick Clifton writes:
 > Hi Guys,
 >   I am applying the following patch to fix a small bug with GAS for
 >   the m32r.  Without this patch applied it will treat a command line
 >   switch of -m32r as if it were -m32rx, and enable the generation of
 >   M32RX instructions and optimisations.
 > 
 >   The fix is to add a specific -m32r option, which directly selects
 >   M32R compatability only.

I'm guessing getopt_long{,_only} allows for unambiguous abbreviations.

You forgot patches to md_show_usage and the relevant .texi files.