Introduce DOSEMU_CFLAGS and ALL_CFLAGS, where ALL_CFLAGS = DOSEMU_CFLAGS CFLAGS
CFLAGS can then be overridden by the user, e.g., using make CFLAGS='-O3'
without breaking compilation. Similar for CPPFLAGS and LDFLAGS.


git-svn-id: https://dosemu.svn.sourceforge.net/svnroot/dosemu/trunk@2057 7758b857-130e-0410-ab9c-d8735a528d18