Convert "remote:" sysroots to "target:" and remove "remote:"

The functionality of "target:" sysroots is a superset of the
functionality of "remote:" sysroots.  This commit causes the
"set sysroot" command to rewrite "remote:" sysroots as "target:"
sysroots and replaces "remote:" specific code with "target:"
specific code where still necessary.

gdb/ChangeLog:

	* remote.h (REMOTE_SYSROOT_PREFIX): Remove definition.
	(remote_filename_p): Remove declaration.
	(remote_bfd_open): Likewise.
	* remote.c (remote_bfd_iovec_open): Remove function.
	(remote_bfd_iovec_close): Likewise.
	(remote_bfd_iovec_pread): Likewise.
	(remote_bfd_iovec_stat): Likewise.
	(remote_filename_p): Likewise.
	(remote_bfd_open): Likewise.
	* symfile.h (gdb_bfd_open_maybe_remote): Remove declaration.
	* symfile.c (separate_debug_file_exists): Use gdb_bfd_open.
	(gdb_bfd_open_maybe_remote): Remove function.
	(symfile_bfd_open):  Replace remote filename check with
	target filename check.
	(reread_symbols): Use gdb_bfd_open.
	* build-id.c (gdbcore.h): New include.
	(build_id_to_debug_bfd): Use gdb_bfd_open.
	* infcmd.c (attach_command_post_wait): Remove remote filename
	check.
	* solib.c (solib_find): Replace remote-specific handling with
	target-specific handling.  Update comments where necessary.
	(solib_bfd_open): Replace remote-specific handling with
	target-specific handling.
	(gdb_sysroot_changed): New function.
	(_initialize_solib): Call the above when gdb_sysroot changes.
	* windows-tdep.c (gdbcore.h): New include.
	(windows_xfer_shared_library): Use gdb_bfd_open.

gdb/remote.c

@@ -10180,113 +10180,6 @@ remote_hostio_close_cleanup (void *opaque)
   remote_hostio_close (find_target_at (process_stratum), fd, &remote_errno);
 }
 
-
-static void *
-remote_bfd_iovec_open (struct bfd *abfd, void *open_closure)
-{
-  const char *filename = bfd_get_filename (abfd);
-  int fd, remote_errno;
-  int *stream;
-
-  gdb_assert (remote_filename_p (filename));
-
-  fd = remote_hostio_open (find_target_at (process_stratum),
-			   filename + 7, FILEIO_O_RDONLY, 0, &remote_errno);
-  if (fd == -1)
-    {
-      errno = remote_fileio_errno_to_host (remote_errno);
-      bfd_set_error (bfd_error_system_call);
-      return NULL;
-    }
-
-  stream = xmalloc (sizeof (int));
-  *stream = fd;
-  return stream;
-}
-
-static int
-remote_bfd_iovec_close (struct bfd *abfd, void *stream)
-{
-  int fd = *(int *)stream;
-  int remote_errno;
-
-  xfree (stream);
-
-  /* Ignore errors on close; these may happen if the remote
-     connection was already torn down.  */
-  remote_hostio_close (find_target_at (process_stratum), fd, &remote_errno);
-
-  /* Zero means success.  */
-  return 0;
-}
-
-static file_ptr
-remote_bfd_iovec_pread (struct bfd *abfd, void *stream, void *buf,
-			file_ptr nbytes, file_ptr offset)
-{
-  int fd = *(int *)stream;
-  int remote_errno;
-  file_ptr pos, bytes;
-
-  pos = 0;
-  while (nbytes > pos)
-    {
-      bytes = remote_hostio_pread (find_target_at (process_stratum),
-				   fd, (gdb_byte *) buf + pos, nbytes - pos,
-				   offset + pos, &remote_errno);
-      if (bytes == 0)
-        /* Success, but no bytes, means end-of-file.  */
-        break;
-      if (bytes == -1)
-	{
-	  errno = remote_fileio_errno_to_host (remote_errno);
-	  bfd_set_error (bfd_error_system_call);
-	  return -1;
-	}
-
-      pos += bytes;
-    }
-
-  return pos;
-}
-
-static int
-remote_bfd_iovec_stat (struct bfd *abfd, void *stream, struct stat *sb)
-{
-  int fd = *(int *) stream;
-  int remote_errno;
-  int result;
-
-  result = remote_hostio_fstat (find_target_at (process_stratum),
-				fd, sb, &remote_errno);
-
-  if (result == -1)
-    {
-      errno = remote_fileio_errno_to_host (remote_errno);
-      bfd_set_error (bfd_error_system_call);
-    }
-
-  return result;
-}
-
-int
-remote_filename_p (const char *filename)
-{
-  return startswith (filename, REMOTE_SYSROOT_PREFIX);
-}
-
-bfd *
-remote_bfd_open (const char *remote_file, const char *target)
-{
-  bfd *abfd = gdb_bfd_openr_iovec (remote_file, target,
-				   remote_bfd_iovec_open, NULL,
-				   remote_bfd_iovec_pread,
-				   remote_bfd_iovec_close,
-				   remote_bfd_iovec_stat);
-
-  return abfd;
-}
-
 void
 remote_file_put (const char *local_file, const char *remote_file, int from_tty)
 {