sigandset/sigorset: do not check for NULL pointers.

that way it's consistent with existing sig* functions, and saves
some code size.

src/signal/sigandset.c

 #define _GNU_SOURCE
 #include <signal.h>
-#include <errno.h>
 
 #define SST_SIZE (_NSIG/8)
 
 int sigandset(sigset_t *dest, sigset_t *left, sigset_t *right)
 {
-	if(!dest || !left || !right) {
-		errno = EINVAL;
-		return -1;
-	}
 	unsigned long i = 0, *d = (void*) dest, *l = (void*) left, *r = (void*) right;
 	for(; i < SST_SIZE; i++) d[i] = l[i] & r[i];
 	return 0;

src/signal/sigorset.c

 #define _GNU_SOURCE
 #include <signal.h>
-#include <errno.h>
 
 #define SST_SIZE (_NSIG/8)
 
 int sigorset(sigset_t *dest, sigset_t *left, sigset_t *right)
 {
-	if(!dest || !left || !right) {
-		errno = EINVAL;
-		return -1;
-	}
 	unsigned long i = 0, *d = (void*) dest, *l = (void*) left, *r = (void*) right;
 	for(; i < SST_SIZE; i++) d[i] = l[i] | r[i];
 	return 0;