tccpp.c: fix endless loop
tccpp.c: fix endless loop

Perhaps a better fix would be to ensure tok is set to TOK_EOF rather
than 0 at the end of a macro stream.

This partially fixes test2 of the examples given in:
http://lists.nongnu.org/archive/html/tinycc-devel/2015-05/msg00002.html

It's still failing, but at least it's not running out of memory now.

andreiw/tinycc,mingodad/tinycc,metaeducation/tcc,andrewchambers/tccmirror,run4flat/tinycc,andreiw/tinycc,run4flat/tinycc,avih/tinycc,run4flat/tinycc,metaeducation/tcc,mirror/tinycc,seyko2/tinycc,run4flat/tinycc,fstudio/tinycc,seyko2/tinycc,andrewchambers/tccmirror,avih/tinycc,avih/tinycc,run4flat/tinycc,andrewchambers/tccmirror,metaeducation/tcc,mirror/tinycc,metaeducation/tcc,avih/tinycc,code4game/tinycc,seyko2/tinycc,andrewchambers/tccmirror,seyko2/tinycc,fstudio/tinycc,fstudio/tinycc,mingodad/tinycc,code4game/tinycc,mirror/tinycc,mingodad/tinycc,fstudio/tinycc,fstudio/tinycc,mirror/tinycc,andrewchambers/tccmirror,seyko2/tinycc,mingodad/tinycc,andreiw/tinycc,metaeducation/tcc,code4game/tinycc