[binutils-gdb] Implement mount namespace support for native Linux targets

[sergiodj+buildbot at redhat dot com]

*** TEST RESULTS FOR COMMIT 7a6a173129107538574949116c0ce1c0ead589b4 ***

Author: Gary Benson <gbenson@redhat.com>
Branch: master
Commit: 7a6a173129107538574949116c0ce1c0ead589b4

Implement mount namespace support for native Linux targets
This commit allows GDB to access executables and shared libraries
on native Linux targets where GDB and the inferior have different
mount namespaces.

gdb/ChangeLog:

	* linux-nat.c (nat/linux-namespaces.h): New include.
	(fileio.h): Likewise.
	(linux_nat_filesystem_is_local): New function.
	(linux_nat_fileio_pid_of): Likewise.
	(linux_nat_fileio_open): Likewise.
	(linux_nat_fileio_readlink): Likewise.
	(linux_nat_fileio_unlink): Likewise.
	(linux_nat_add_target): Initialize to_filesystem_is_local,
	to_fileio_open, to_fileio_readlink and to_fileio_unlink.
	(_initialize_linux_nat): New "set/show debug linux-namespaces"
	commands.
	* NEWS: Mention new "set/show debug linux-namespaces" commands.

gdb/doc/ChangeLog:

	* gdb.texinfo (Debugging Output): Document the "set/show debug
	linux-namespaces" command.