x86-64: Fix TLSDESC relaxation for x32

x86-64: Fix TLSDESC relaxation for x32

For x32, we must encode "lea x@TLSDESC(%rip), %reg" with a REX prefix
even if it isn't required.  Otherwise linker can’t safely perform
GDesc -> IE/LE optimization.  X32 TLSDESC sequences can be:

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

should relaxed to

0f 1f 00		nopl	(%rax)

For GDesc -> LE transition,

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

should relaxed to

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

For GDesc -> IE transition,

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

should relaxed to

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

bfd/

	PR ld/25416
	* elf64-x86-64.c (elf_x86_64_check_tls_transition): Support
	"rex leal x@tlsdesc(%rip), %reg" and "call *x@tlsdesc(%eax)" in
	X32 mode.
	(elf_x86_64_relocate_section): In x32 mode, for GDesc -> LE
	transition, relax "rex leal x@tlsdesc(%rip), %reg" to
	"rex movl $x@tpoff, %reg", for GDesc -> IE transition, relax
	"rex leal x@tlsdesc(%rip), %reg" to
	"rex movl x@gottpoff(%rip), %eax".  For both transitions, relax
	"call *(%eax)" to "nopl (%rax)".

gas/

	PR ld/25416
	* config/tc-i386.c (output_insn): Add a dummy REX_OPCODE prefix
	for lea with R_X86_64_GOTPC32_TLSDESC relocation when generating
	x32 object.
	* testsuite/gas/i386/ilp32/x32-tls.d: Updated.
	* testsuite/gas/i386/ilp32/x32-tls.s: Add tests for lea with
	R_X86_64_GOTPC32_TLSDESC relocation.

ld/

	PR ld/25416
	* testsuite/ld-x86-64/pr25416-1.s: New file
	* testsuite/ld-x86-64/pr25416-1a.d: Likewise.
	* testsuite/ld-x86-64/pr25416-1b.d: Likewise.
	* testsuite/ld-x86-64/pr25416-1.s: Likewise.
	* testsuite/ld-x86-64/pr25416-2.s: Likewise.
	* testsuite/ld-x86-64/pr25416-2a.d: Likewise.
	* testsuite/ld-x86-64/pr25416-2b.d: Likewise.
	* testsuite/ld-x86-64/pr25416-3.d: Likewise.
	* testsuite/ld-x86-64/pr25416-3.s: Likewise.
	* testsuite/ld-x86-64/pr25416-4.d: Likewise.
	* testsuite/ld-x86-64/pr25416-4.s: Likewise.
	* testsuite/ld-x86-64/pr25416-5a.c: Likewise.
	* testsuite/ld-x86-64/pr25416-5b.s: Likewise.
	* testsuite/ld-x86-64/pr25416-5c.s: Likewise.
	* testsuite/ld-x86-64/pr25416-5d.s: Likewise.
	* testsuite/ld-x86-64/pr25416-5e.s: Likewise.
	* testsuite/ld-x86-64/x86-64.exp: Run PR ld/25416 tests.