8l: correct Plan 9 compiler warnings

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4390047

src/cmd/8l/asm.c

@@ -307,6 +307,7 @@ elfsetupplt(void)
 int
 archreloc(Reloc *r, Sym *s, vlong *val)
 {
+	USED(s);
 	switch(r->type) {
 	case D_CONST:
 		*val = r->add;
@@ -644,7 +645,7 @@ asmb(void)
 {
 	int32 v, magic;
 	int a, dynsym;
-	uint32 va, fo, w, symo, startva, machlink;
+	uint32 symo, startva, machlink;
 	ElfEhdr *eh;
 	ElfPhdr *ph, *pph;
 	ElfShdr *sh;
@@ -776,7 +777,6 @@ asmb(void)
 		lputb(0L);
 		lputb(~0L);			/* gp value ?? */
 		break;
-		lputl(0);			/* x */
 	case Hunixcoff:	/* unix coff */
 		/*
 		 * file header
@@ -892,13 +892,10 @@ asmb(void)
 			debug['d'] = 1;
 
 		eh = getElfEhdr();
-		fo = HEADR;
 		startva = INITTEXT - HEADR;
-		va = startva + fo;
-		w = segtext.filelen;
 
 		/* This null SHdr must appear before all others */
-		sh = newElfShdr(elfstr[ElfStrEmpty]);
+		newElfShdr(elfstr[ElfStrEmpty]);
 
 		/* program header info */
 		pph = newElfPhdr();
@@ -1214,6 +1211,6 @@ genasmsym(void (*put)(Sym*, char*, int, vlong, vlong, int, Sym*))
 				put(nil, a->asym->name, 'p', a->aoffset, 0, 0, a->gotype);
 	}
 	if(debug['v'] || debug['n'])
-		Bprint(&bso, "symsize = %ud\n", symsize);
+		Bprint(&bso, "symsize = %uld\n", symsize);
 	Bflush(&bso);
 }