tools/rtla: Remove unused optional option_index

The longindex argument of getopt_long() is optional
and tied to the unused local variable option_index.

Remove it to shorten the four longest functions
and make the code neater.

Signed-off-by: Costa Shulyupin <costa.shul@redhat.com>
Reviewed-by: Tomas Glozar <tglozar@redhat.com>
Link: https://lore.kernel.org/r/20251002123553.389467-2-costa.shul@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>

tools/tracing/rtla/src/osnoise_hist.c

@@ -524,11 +524,8 @@ static struct common_params
 			{0, 0, 0, 0}
 		};
 
-		/* getopt_long stores the option index here. */
-		int option_index = 0;
-
 		c = getopt_long(argc, argv, "a:c:C::b:d:e:E:DhH:p:P:r:s:S:t::T:01234:5:6:7:",
-				 long_options, &option_index);
+				 long_options, NULL);
 
 		/* detect the end of the options. */
 		if (c == -1)

tools/tracing/rtla/src/osnoise_top.c

@@ -376,11 +376,8 @@ struct common_params *osnoise_top_parse_args(int argc, char **argv)
 			{0, 0, 0, 0}
 		};
 
-		/* getopt_long stores the option index here. */
-		int option_index = 0;
-
 		c = getopt_long(argc, argv, "a:c:C::d:De:hH:p:P:qr:s:S:t::T:0:1:2:3:",
-				 long_options, &option_index);
+				 long_options, NULL);
 
 		/* Detect the end of the options. */
 		if (c == -1)

tools/tracing/rtla/src/timerlat_hist.c

@@ -840,11 +840,8 @@ static struct common_params
 			{0, 0, 0, 0}
 		};
 
-		/* getopt_long stores the option index here. */
-		int option_index = 0;
-
 		c = getopt_long(argc, argv, "a:c:C::b:d:e:E:DhH:i:knp:P:s:t::T:uU0123456:7:8:9\1\2:\3:",
-				 long_options, &option_index);
+				 long_options, NULL);
 
 		/* detect the end of the options. */
 		if (c == -1)

tools/tracing/rtla/src/timerlat_top.c

@@ -604,11 +604,8 @@ static struct common_params
 			{0, 0, 0, 0}
 		};
 
-		/* getopt_long stores the option index here. */
-		int option_index = 0;
-
 		c = getopt_long(argc, argv, "a:c:C::d:De:hH:i:knp:P:qs:t::T:uU0:1:2:345:6:7:",
-				 long_options, &option_index);
+				 long_options, NULL);
 
 		/* detect the end of the options. */
 		if (c == -1)