remove support for the interix target

contrib/ChangeLog:

2016-06-21  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* config-list.mk: Remove interix target.

libgcc/ChangeLog:

2016-06-21  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* config.host: Remove interix support.
	* config/i386/t-interix: Remove.

config/ChangeLog:

2016-06-21  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* elf.m4: Remove interix support.
	* picflag.m4: Likewise.

fixincludes/ChangeLog:

2016-06-21  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* mkfixinc.sh: Remove interix support.

gcc/ChangeLog:

2016-06-21  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* config.gcc: Remove interix support.
	* config/i386/i386-interix.h: Remove.
	* config/i386/interix.opt: Remove.
	* config/i386/t-interix: Remove.
	* configure: Regenerate.
	* configure.ac: Remove interix support.
	* doc/install.texi: Remove interix documentation.

gcc/testsuite/ChangeLog:

2016-06-21  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* gcc.dg/attr-ms_struct-1.c: Stop testing interix.
	* gcc.dg/attr-ms_struct-2.c: Likewise.
	* gcc.dg/attr-ms_struct-packed1.c: Likewise.
	* gcc.dg/bf-ms-attrib.c: Likewise.
	* gcc.dg/bf-ms-layout-2.c: Likewise.
	* gcc.dg/bf-ms-layout-3.c: Likewise.
	* gcc.dg/bf-ms-layout.c: Likewise.
	* gcc.dg/bf-no-ms-layout.c: Likewise.
	* gcc.target/i386/bitfield1.c: Likewise.
	* gcc.target/i386/bitfield2.c: Likewise.
	* gcc.target/i386/bitfield3.c: Likewise.

From-SVN: r237660