gdb/sim: add support for exporting memory map

This allows gdb to quickly dump & process the memory map that the sim
knows about.  This isn't fully accurate, but is largely limited by the
gdb memory map format.  While the sim supports RWX bits, gdb can only
handle RW or RO regions.

gdb/remote-sim.c

@@ -42,6 +42,7 @@
 #include "readline/readline.h"
 #include "gdbthread.h"
 #include "gdbsupport/byte-vector.h"
+#include "memory-map.h"
 
 /* Prototypes */
 
@@ -164,6 +165,7 @@ struct gdbsim_target final
 
   bool has_all_memory ()  override;
   bool has_memory ()  override;
+  std::vector<mem_region> memory_map () override;
 
 private:
   sim_inferior_data *get_inferior_data_by_ptid (ptid_t ptid,
@@ -1270,6 +1272,22 @@ gdbsim_target::has_memory ()
   return true;
 }
 
+/* Get memory map from the simulator.  */
+
+std::vector<mem_region>
+gdbsim_target::memory_map ()
+{
+  struct sim_inferior_data *sim_data
+    = get_sim_inferior_data (current_inferior (), SIM_INSTANCE_NEEDED);
+  std::vector<mem_region> result;
+  gdb::unique_xmalloc_ptr<char> text (sim_memory_map (sim_data->gdbsim_desc));
+
+  if (text != nullptr)
+    result = parse_memory_map (text.get ());
+
+  return result;
+}
+
 void _initialize_remote_sim ();
 void
 _initialize_remote_sim ()