Add support for loadable profiles

Split the only existing profile, tiobench, into this setup.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/options.c b/options.c
index 0e57e52..03b2437 100644
--- a/options.c
+++ b/options.c
@@ -1726,14 +1726,8 @@
 	},
 	{
 		.name	= "profile",
-		.type	= FIO_OPT_STR,
+		.type	= FIO_OPT_STR_STORE,
 		.off1	= td_var_offset(profile),
-		.posval = {
-			  { .ival = "tiobench",
-			    .oval = PROFILE_TIOBENCH,
-			    .help = "Perform tiobench like test",
-			  },
-		},
 		.help	= "Select a specific builtin performance test",
 	},
 	{