WARNS?=6 cleanup for [gs]et[fp]mac:

- Constify structure members that should not be changed
	  during process.
	- Apply static where needed
	- signed/unsigned madness
	- Bump WARNS?= levels from 2 to 6

(this is a diff reduction for a subsequent commit against these
Makefile's)

usr.sbin/getfmac/Makefile

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

usr.sbin/getfmac/getfmac.c

@@ -46,7 +46,7 @@
 
 #define	MAXELEMENTS	32
 
-void
+static void
 usage(void)
 {
 

usr.sbin/getpmac/Makefile

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

usr.sbin/getpmac/getpmac.c

@@ -46,7 +46,7 @@
 
 #define	MAXELEMENTS	32
 
-void
+static void
 usage(void)
 {
 

usr.sbin/setfmac/Makefile

@@ -5,6 +5,6 @@ LINKS=	${BINDIR}/setfmac ${BINDIR}/setfsmac
 MAN=	setfmac.8 setfsmac.8
 SRCS=   setfmac.c
 
-WARNS?=	2
+WARNS?=	6
 
 .include <bsd.prog.mk>

usr.sbin/setfmac/setfmac.c

@@ -54,7 +54,7 @@ struct label_spec {
 		regex_t regex;	/* compiled regular expression to match */
 		char *regexstr;	/* uncompiled regular expression */
 		mode_t mode;	/* mode to possibly match */
-		char *modestr;	/* print-worthy ",-?" mode string */
+		const char *modestr;	/* print-worthy ",-?" mode string */
 		char *mactext;	/* MAC label to apply */
 		int flags;	/* miscellaneous flags */
 #define		F_DONTLABEL	0x01
@@ -195,13 +195,13 @@ usage(int is_setfmac)
 	exit(1);
 }
 
-int
+static int
 chomp_line(char **line, size_t *linesize)
 {
 	char *s;
 	int freeme = 0;
 	
-	for (s = *line; s - *line < *linesize; s++) {
+	for (s = *line; (unsigned)(s - *line) < *linesize; s++) {
 		if (!isspace(*s))
 			break;
 	}

usr.sbin/setpmac/Makefile

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

usr.sbin/setpmac/setpmac.c

@@ -46,7 +46,7 @@
 
 #define	MAXELEMENTS	32
 
-void
+static void
 usage(void)
 {
 
@@ -57,7 +57,7 @@ usage(void)
 int
 main(int argc, char *argv[])
 {
-	char *shell;
+	const char *shell;
 	mac_t label;
 	int error;