llib-lc omits popen/pclose

[utzoo!henry]

The standard lint library omits declarations for the functions in
popen(3).  Here are suitable entries for /usr/lib/llib-lc:

	FILE	*popen(c,t) char *c, *t; { return(stdin); }
	int	pclose(s) FILE *s; { return(0); }