* buildsym.c (scan_file_globals): Beware the null file.

* buildsym.c (scan_file_globals):  Beware the null file.
Fix from Jim Williams.

* stack.c (return_command):  Evaluate expression *before* popping
off the stack frames!  Fix inspired by Jim Williams.
(up_silently_command, down_silently_command):  No sel frame is error.

* defs.h (memcpy, memset):  Conditionalize decls on
#ifndef MEM_FNS_DECLARED, since DECstation differs.
(alloca):  Break out the STDC and non-STDC alloca cases, to make
it work on old preprocessors as well as "picky ANSI" ones.
* xm-mips.h (memcpy, memset):  Declare, and set MEM_FNS_DECLARED.

* mips-tdep.c (heuristic_proc_start):  Zero arg produces zero.
* utils.c (fputs_demangled):  Rename SLOP since DECstation system
header files define it!