sim: standardize sim_create_inferior handling of argv a bit more

For targets that process argv in sim_create_inferior, improve the code:
- provide more details in the comment
- make the check for when to re-init more robust
- clean out legacy sim_copy_argv code

This will be cleaned up more in the future when we have a common inferior
creation function, but at least help new ports get it right until then.

sim/m32r/ChangeLog

@@ -1,3 +1,7 @@
+2015-12-26  Mike Frysinger  <vapier@gentoo.org>
+
+	* sim-if.c (sim_create_inferior): Replace old #if 0 code with dupargv.
+
 2015-12-25  Mike Frysinger  <vapier@gentoo.org>
 
 	* configure.ac (SIM_AC_OPTION_HARDWARE): Add m32r_cache & m32r_uart.

sim/m32r/sim-if.c

@@ -199,10 +199,15 @@ sim_create_inferior (sd, abfd, argv, envp)
                     m32r_decode_gdb_ctrl_regnum(SPU_REGNUM), 0x1f00000);
 #endif
 
-#if 0
-  STATE_ARGV (sd) = sim_copy_argv (argv);
-  STATE_ENVP (sd) = sim_copy_argv (envp);
-#endif
+  /* Standalone mode (i.e. `run`) will take care of the argv for us in
+     sim_open() -> sim_parse_args().  But in debug mode (i.e. 'target sim'
+     with `gdb`), we need to handle it because the user can change the
+     argv on the fly via gdb's 'run'.  */
+  if (STATE_PROG_ARGV (sd) != argv)
+    {
+      freeargv (STATE_PROG_ARGV (sd));
+      STATE_PROG_ARGV (sd) = dupargv (argv);
+    }
 
   return SIM_RC_OK;
 }