vc: word align automatics

theres code that assumes one can dereference a char[] buffer on the stack
as a long (ghostscript gxblend.c), so make sure all automatics on the stack
are word aligned. this is not strictrly neccesary, but avoids some
trouble with unportable code.

sys/src/cmd/vc/swt.c

@@ -587,6 +587,7 @@ align(long i, Type *t, int op)
 	case Aaut3:	/* total allign of automatic */
 		o = align(o, t, Ael1);
 		o = align(o, t, Ael2);
+		w = SZ_LONG;
 		break;
 	}
 	o = round(o, w);