xsm/flask: mkflash.sh: Use const when generating initial_sid_to_string[]

The array initial_sid_to_string is storing pointer to literal strings
and is not meant to be modified. So change the type of the variable
to "const char * const ...[]".

Signed-off-by: Julien Grall <jgrall@amazon.com>
Ack-by: Daniel P. Smith <dpsmith@apertussolutions.com>

xen/xsm/flask/policy/mkflask.sh

@@ -34,7 +34,7 @@ BEGIN	{
 		printf("/*\n * Security object class definitions\n */\n") > debugfile;
 		printf("    S_(\"null\")\n") > debugfile;
 		printf("/* This file is automatically generated.  Do not edit. */\n") > debugfile2;
-		printf("static char *initial_sid_to_string[] =\n{\n") > debugfile2;
+		printf("static const char * const initial_sid_to_string[] =\n{\n") > debugfile2;
 		printf("    \"null\",\n") > debugfile2;
 	}
 /^[ \t]*#/	{