WARNS=2 and style(9) cleanup:

o prototype usage()
o move BUFSIZE define above the functions
o nuke externs that are defined in unistd.h

Approved by:	rwatson
Obtained from:	TrustedBSD Project

usr.sbin/getextattr/Makefile

@@ -3,4 +3,6 @@
 PROG=	getextattr
 MAN=	getextattr.8
 
+WARNS?=	2
+
 .include <bsd.prog.mk>

usr.sbin/getextattr/getextattr.c

@@ -38,6 +38,10 @@
 #include <unistd.h>
 #include <vis.h>
 
+#define BUFSIZE	2048
+
+void usage(void);
+
 void
 usage(void)
 {
@@ -47,11 +51,6 @@ usage(void)
 	exit(-1);
 }
 
-extern char	*optarg;
-extern int	optind;
-
-#define BUFSIZE	2048
-
 int
 main(int argc, char *argv[])
 {