two more if(h<0) that gcc 4.3 -O2 miscompiles

R=r
https://golang.org/cl/160044

src/cmd/cc/lexbody

@@ -226,8 +226,7 @@ lookup(void)
 	for(p=symb; c = *p; p++)
 		h = h+h+h + c;
 	l = (p - symb) + 1;
-	if(h < 0)
-		h = ~h;
+	h &= 0xffffff;
 	h %= NHASH;
 	c = symb[0];
 	for(s = hash[h]; s != S; s = s->link) {

src/libmach/obj.c

@@ -257,9 +257,7 @@ objlookup(int id, char *name, int type, uint sig)
 	h = *name;
 	for(cp = name+1; *cp; h += *cp++)
 		h *= HASHMUL;
-	if(h < 0)
-		h = ~h;
-	h &= (NHASH-1);
+	h &= NHASH-1;
 	if (type == 'U' || type == 'b' || islocal(type)) {
 		for(sp = hash[h]; sp; sp = sp->next)
 			if(strcmp(sp->s.name, name) == 0) {