These subdirs have unique configure scripts to do some compiler tests.
The checks should work for all targets, so hoist them up to the top
libgloss dir. This should allow us to delete these subdir configure
scripts.
It means the top-level gains autoheader support, but that's fine.
It wasn't exporting any defines previously (i.e. -D into CPPFLAGS),
and all of the defines it now exports are only used by code in the
libnosys subdir which was expecting to have a config.h.
bfin - Analog Devices Blackfin processor.
sparc - Fujitsu Sparclite board. Works on the ex930, ex931, ex933
hp74x - Hewlett Packard HP742 board. Also some support for the hp743.
m68hc11 - Motorola 68HC11 or 68HC12 support.
m68k - Motorola MVME135 and IDP board. For CPU32 systems.
mep - Toshiba Media Processor.
pa - WinBond and Oki boards with a PA.
mips - R3000 support. Array Tech LSI33k based RAID disk controller.
lm32 - Lattice Mico32 simulator.
epiphany - Adapteva Epiphany multicore processor.
or1k - OpenRISC 1000 processor.
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