gc: fix mkbuiltin

Broken by Plan 9 changes.

R=ken2
CC=golang-dev
https://golang.org/cl/4896050

src/cmd/gc/Makefile

@@ -65,3 +65,7 @@ opnames.h:	mkopnames go.h
 	./mkopnames go.h >opnames.h
 
 CLEANFILES+=*.[568] [568].out y1.tab.c yerr.h mkbuiltin1 builtin.c _builtin.c opnames.h
+
+mkbuiltin1: mkbuiltin1.$O
+	$(HOST_LD) -o $@ mkbuiltin1.$O -L"$(GOROOT)"/lib -lbio -l9 -lm $(HOST_LDFLAGS)
+

src/cmd/gc/mkbuiltin

@@ -16,7 +16,7 @@ if [ -z "$GC" ]; then
 	exit 1
 fi
 
-gcc -o mkbuiltin1 mkbuiltin1.c
+gomake mkbuiltin1
 rm -f _builtin.c
 for i in runtime unsafe
 do

src/cmd/gc/mkbuiltin1.c

@@ -10,7 +10,7 @@
 
 void esc(char*);
 
-int
+void
 main(int argc, char **argv)
 {
 	char *name;
@@ -64,13 +64,13 @@ begin:
 		}
 
 		esc(p);
-		printf("\\n\"\n", p);
+		printf("\\n\"\n");
 	}
 	sysfatal("did not find end of imports\n");
 
 end:
 	printf("\t\"$$\\n\";\n");
-	return 0;
+	exits(0);
 }
 
 void