cmd/gc, cmd/ld: fix Plan 9 warnings

warning: /usr/go/src/cmd/gc/obj.c:23 format mismatch -10d VLONG, arg 9
warning: /usr/go/src/cmd/gc/plive.c:1680 set and not used: printed
warning: /usr/go/src/cmd/ld/lib.c:332 non-interruptable temporary
warning: /usr/go/src/cmd/ld/lib.c:338 non-interruptable temporary

R=rsc
CC=golang-codereviews
https://golang.org/cl/53820046

src/cmd/gc/obj.c

@@ -20,7 +20,7 @@ enum
 static void
 formathdr(char *arhdr, char *name, vlong size)
 {
-	snprint(arhdr, ArhdrSize, "%-16s%-12d%-6d%-6d%-8o%-10d`",
+	snprint(arhdr, ArhdrSize, "%-16s%-12d%-6d%-6d%-8o%-10lld`",
 		name, 0, 0, 0, 0644, size);
 	arhdr[ArhdrSize-1] = '\n'; // overwrite \0 written by snprint
 }

src/cmd/gc/plive.c

@@ -1676,10 +1676,9 @@ printbitset(int printed, char *name, Array *vars, Bvec *bits)
 		if(!bvget(bits, i))
 			continue;
 		if(!started) {
-			if(!printed) {
-				printed = 1;
+			if(!printed)
 				print("\t");
-			} else
+			else
 				print(" ");
 			started = 1;
 			printed = 1;

src/cmd/ld/lib.c

@@ -329,13 +329,15 @@ objfile(char *file, char *pkg)
 	
 	/* skip over optional __.GOSYMDEF and process __.PKGDEF */
 	off = Boffset(f);
-	if((l = nextar(f, off, &arhdr)) <= 0) {
+	l = nextar(f, off, &arhdr);
+	if(l <= 0) {
 		diag("%s: short read on archive file symbol header", file);
 		goto out;
 	}
 	if(strncmp(arhdr.name, symname, strlen(symname)) == 0) {
 		off += l;
-		if((l = nextar(f, off, &arhdr)) <= 0) {
+		l = nextar(f, off, &arhdr);
+		if(l <= 0) {
 			diag("%s: short read on archive file symbol header", file);
 			goto out;
 		}