* defs.h: Include ansidecl.h and PARAMS macro. Use PARAMS

* defs.h:  Include ansidecl.h and PARAMS macro.  Use PARAMS
to make prototypes for all functions declared here.
* cplus-dem.c:  Avoid declaring xmalloc and xrealloc.
* c-exp.y:  Rename SIGNED, OR, and AND to avoid conflict.
* environ.c:  Include <stdio.h> before defs.h.  Minor cleanup.
* ieee-float.h:  Use PARAMS for prototypes; make some params const.
* ieee-float.c, valarith.c:  Include <stdio.h>.  Lint.  b*=>mem*.
* m2-exp.y:  Remove unused CONST; Rename OR and AND.
* utils.c:  Avoid declaring malloc and realloc.  Lint.
(request_quit):  Accept signal-number parameter.