Move files needed for the C bootstrap into ./bootstrap/c

--HG--
rename : buffer.c => bootstrap/c/buffer.c
rename : chartab.h => bootstrap/c/chartab.h
rename : eval2.c => bootstrap/c/eval.c
rename : gc.c => bootstrap/c/gc.c
rename : gc.h => bootstrap/c/gc.h
rename : libgc.c => bootstrap/c/libgc.c
rename : mkosdefs.c => bootstrap/c/mkosdefs.c
rename : wcs.c => bootstrap/c/wcs.c
Added a .hgignore