Eliminate a compiler warning with gcc 4.2 by constifying a char *

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@76176 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/manager.c

@@ -819,7 +819,7 @@ static int get_perm(const char *instr)
 	return ret;
 }
 
-static int ast_is_number(char *string) 
+static int ast_is_number(const char *string) 
 {
 	int ret = 1, x = 0;
 
@@ -840,7 +840,7 @@ static int strings_to_mask(const char *string)
 {
 	int x, ret = -1;
 	
-	x = ast_is_number((char *) string);
+	x = ast_is_number(string);
 
 	if (x)
 		ret = x;