Tweak "Using the running image of ..." output

Currently, "info files" and "info program" on a few native targets
show:

 (gdb) info files
 Symbols from "/home/pedro/gdb/tests/threads".
 Native process:
	 Using the running image of child Thread 0x7ffff7d89740 (LWP 1097968).
					  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 ...

 (gdb) info program
	 Using the running image of child Thread 0x7ffff7d89740 (LWP 1097968).
					  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Program stopped at 0x555555555278.
 ...


This patch changes them to:

 (gdb) info files
 Symbols from "/home/pedro/gdb/tests/threads".
 Native process:
	 Using the running image of child process 1097968.
	                                  ^^^^^^^^^^^^^^^
 ...

 (gdb) info program
	 Using the running image of child process 1097968.
	                                  ^^^^^^^^^^^^^^^
 Program stopped at 0x555555555278.
 ...


... which I think makes a lot more sense in this context.  The "info
program" manual entry even says:

  "Display information about the status of your program: whether it is
   running or not, what process it is, and why it stopped."
                        ^^^^^^^^^^^^^

This change affects ptrace targets, procfs targets, and Windows.

Change-Id: I6aab061ff494a84ba3398cf98fd49efd7a6ec1ca

gdb/inf-ptrace.c

@@ -522,7 +522,7 @@ inf_ptrace_target::files_info ()
 
   gdb_printf (_("\tUsing the running image of %s %s.\n"),
 	      inf->attach_flag ? "attached" : "child",
-	      target_pid_to_str (inferior_ptid).c_str ());
+	      target_pid_to_str (ptid_t (inf->pid)).c_str ());
 }
 
 std::string

gdb/nto-procfs.c

@@ -658,7 +658,7 @@ nto_procfs_target::files_info ()
 
   gdb_printf ("\tUsing the running image of %s %s via %s.\n",
 	      inf->attach_flag ? "attached" : "child",
-	      target_pid_to_str (inferior_ptid).c_str (),
+	      target_pid_to_str (ptid_t (inf->pid)).c_str (),
 	      (nodestr != NULL) ? nodestr : "local node");
 }
 

gdb/procfs.c

@@ -2533,7 +2533,7 @@ procfs_target::files_info ()
 
   gdb_printf (_("\tUsing the running image of %s %s via /proc.\n"),
 	      inf->attach_flag? "attached": "child",
-	      target_pid_to_str (inferior_ptid).c_str ());
+	      target_pid_to_str (ptid_t (inf->pid)).c_str ());
 }
 
 /* Make it die.  Wait for it to die.  Clean up after it.  Note: this

gdb/windows-nat.c

@@ -2157,7 +2157,7 @@ windows_nat_target::files_info ()
 
   gdb_printf ("\tUsing the running image of %s %s.\n",
 	      inf->attach_flag ? "attached" : "child",
-	      target_pid_to_str (inferior_ptid).c_str ());
+	      target_pid_to_str (ptid_t (inf->pid)).c_str ());
 }
 
 /* Modify CreateProcess parameters for use of a new separate console.