From libreoffice: remove problematic Cygwin env vars.
From libreoffice: deprecate os2-gcc in make.cmd.
From libreoffice: disable double-% warning.
From libreoffice: support os2 in startup/unix/Makefile.*
From libreoffice: check fread return code.
From libreoffice: make loop-counter "register".
From libreoffice: spelling, RCS tag removal.