5l, 6l, 8l, ld: remove memory leaks

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5569085

src/cmd/5l/asm.c

@@ -91,6 +91,7 @@ needlib(char *name)
 	/* reuse hash code in symbol table */
 	p = smprint(".dynlib.%s", name);
 	s = lookup(p, 0);
+	free(p);
 	if(s->type == 0) {
 		s->type = 100;	// avoid SDATA, etc.
 		return 1;

src/cmd/6l/asm.c

@@ -112,6 +112,7 @@ needlib(char *name)
 	/* reuse hash code in symbol table */
 	p = smprint(".elfload.%s", name);
 	s = lookup(p, 0);
+	free(p);
 	if(s->type == 0) {
 		s->type = 100;	// avoid SDATA, etc.
 		return 1;

src/cmd/8l/asm.c

@@ -108,6 +108,7 @@ needlib(char *name)
 	/* reuse hash code in symbol table */
 	p = smprint(".dynlib.%s", name);
 	s = lookup(p, 0);
+	free(p);
 	if(s->type == 0) {
 		s->type = 100;	// avoid SDATA, etc.
 		return 1;

src/cmd/ld/go.c

@@ -482,6 +482,7 @@ loaddynimport(char *file, char *pkg, char *p, int n)
 		if(q)
 			*q++ = '\0';
 		s = lookup(name, 0);
+		free(name);
 		if(s->type == 0 || s->type == SXREF) {
 			s->dynimplib = lib;
 			s->dynimpname = def;