Global Font Lock by default

[Richard M. Stallman]

The main obstacle to enabling Global Font Lock by default
was that it uses more memory and cause an Emacs session to
die sooner.

I've fixed some bugs in the way memory full is handled.  !MEM FULL!
should appear in the mode line once Emacs can't get more Lisp memory.
If you kill things and that results in making space available, !MEM
FULL! should disappear.

However, this does not work.  The reason is that the value
of BYTES_USED, which I believe is obtained from mallinfo,
does not seem to decrease even when a large buffer is killed.

I don't have any documentation for mallinfo.
Can someone send it to me?