* config/m32r/m32r.h: Add support for m32r2 processor.  Including
  a new command line option -m32r2 to select it.
* config/m32r/m32r.c: Add support for the new processor variant.
* config/m32r/m32r.md: Likewise.
* config/m32r/t-m32r: Add m32r2 multilibs.
* doc/invoke.texi: Document the new command line switch.

From-SVN: r74473