Remove m32r{,le}-*-linux* support from GCC

Remove m32r{,le}-*-linux* support from GCC

m32r support never made it to glibc and the support for the Linux kernel
was removed with 4.18. It does not remove much but no reason to keep
around a port which never worked or one which the support in other
projects is gone.

OK? Checked to make sure m32r-linux and m32rle-linux were rejected
when building.

contrib/ChangeLog:

	* config-list.mk: Remove m32r-linux and m32rle-linux
	from the list.

gcc/ChangeLog:

	* config.gcc: Add m32r-*-linux* and m32rle-*-linux*
	to the Unsupported targets list.
	Remove support for m32r-*-linux* and m32rle-*-linux*.
	* config/m32r/linux.h: Removed.
	* config/m32r/t-linux: Removed.

libgcc/ChangeLog:

	* config.host: Remove m32r-*-linux* and m32rle-*-linux*.
	* config/m32r/libgcc-glibc.ver: Removed.
	* config/m32r/t-linux: Removed.