selinux: fix warning in genheaders

Fix const warning in the genheaders script as a result of
changes to the headers, as noted here:

http://linux.derkeiler.com/Mailing-Lists/Kernel/2010-03/msg03977.html

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: James Morris <jmorris@namei.org>

scripts/selinux/genheaders/genheaders.c

@@ -81,7 +81,7 @@ int main(int argc, char *argv[])
 	fprintf(fout, "\n");
 
 	for (i = 1; i < isids_len; i++) {
-		char *s = initial_sid_to_string[i];
+		const char *s = initial_sid_to_string[i];
 		fprintf(fout, "#define SECINITSID_%s", s);
 		for (j = 0; j < max(1, 40 - strlen(s)); j++)
 			fprintf(fout, " ");