gdb support (determined by GNU configure).
* Be less verbose if there are no existing toolchain framework files to
compare (suppress grep "file not found" error)
files. This version is capable of generating these files Properly from
a cross host (subject to having tools and target libs/includes available
ahead of time; to be documented).
Provide a target "bootstrap-libgcc", which will create the files
src/gnu/lib/libgcc/${MACHINE_ARCH}.mk
src/gnu/usr.bin/gcc/arch/${MACHINE_ARCH}/tconfig.h
src/gnu/usr.bin/gcc/arch/${MACHINE_ARCH}/tm.h
...enough to allow libgcc to build so that a bootstrap build to DESTDIR can
take place.