gold: x86-64: Fix TLSDESC relaxation for x32

gold: x86-64: Fix TLSDESC relaxation for x32

X32 TLSDESC sequences can be:

40 8d 05 00 00 00 00	rex lea	foo@TLSDESC(%rip), %reg
...
67 ff 10		call	*foo@TLSCALL(%eax)

or the same sequence as LP64:

48 8d 05 00 00 00 00	lea	foo@TLSDESC(%rip), %reg
...
ff 10			call	*foo@TLSCALL(%rax)

We need to support both sequences for x32.  For both GDesc -> IE/LE
transitions,

67 ff 10		call	*foo@TLSCALL(%eax)

should relaxed to

0f 1f 00		nopl	(%rax)

For GDesc -> LE transition,

40 8d 05 00 00 00 00	rex lea	foo@TLSDESC(%rip), %reg

should relaxed to

40 c7 c0 fc ff ff ff	rex movl $foo@tpoff, %reg

For GDesc -> IE transition,

40 8d 05 00 00 00 00	rex lea	foo@TLSDESC(%rip), %reg

should relaxed to

40 8b 05 00 00 00 00	rex movl foo@gottpoff(%rip), %eax

	PR gold/25426
	* x86_64.cc (Target_x86_64<size>::Relocate::tls_desc_gd_to_ie):
	For x32, relax "rex leal foo@tlsdesc(%rip), %reg" to
	"rex movl foo@gottpoff(%rip), %eax" and relax ""call *(%eax)"
	to "nopl (%rax)".
	(Target_x86_64<size>::Relocate::tls_desc_gd_to_le): For x32,
	relax "rex leal foo@tlsdesc(%rip), %reg" to
	"rex movl foo@tpoff, %eax" and relax "call *foo@tlscall(%eax)"
	to "nopl (%rax)".
	* testsuite/Makefile.am (tls_test_gnu2.o): Depend on
	gcctestdir/as.
	(tls_test_file2_gnu2.o): Likewise.
	(tls_test_c_gnu2.o): Likewise.
	* testsuite/Makefile.in: Regenerated.