libsframe: use proper FRE type when flipping SFrame V3 FREs

flip_sframe_fdes_with_fres_v3 was erroneously using a fixed FRE type
of 0 (= SFRAME_FRE_TYPE_ADDR1) when endianness byte-flipping the FREs,
regardless of the actual FRE type (i.e. ADDR1, ADDR2, or ADDR4).  This
only affected cross builds, where the .sframe section data may needed
to be endianness byte-flipped (e.g. binutils cross-built for s390
64-bit (s390x) on x86-64).

As a consequence objdump/readelf with option --sframe could fail to dump
e.g. s390 64-bit (s390x) .sframe section data on x86-64 with the
following error message:

  Error: SFrame decode failure: Buffer does not contain SFrame data.

The linker ld-sframe test "PR ld/33401 (Step 1: Create relocatable
object and check R_*_NONE)" cross-build for s390 64-bit (s390x) on
x86-64 could fail with ld error message:

  error in tmpdir/StatePlaying.o(.sframe); no .sframe will be created

The linker ld-sframe test "PR ld/33401 (Step 1: Create relocatable
object and check R_*_NONE)" cros-build for s390 64-bit (s390x) on
x86-64 could fail with BDF assertion:

  BFD (GNU Binutils) ... assertion fail .../bfd/elf-sframe.c:153

Add a common cfi-sframe assembler test, that forces a FDE type of
SFRAME_FRE_TYPE_ADDR2.  When the test is run cross-build it may
exercise the SFrame FDE and FDE endianness byte flipping.

libsframe/
	PR ld/33810
	* sframe.c (sframe_decode_fde_attr_v3): Decode and return FRE
	type from FDE attributes.
	(flip_sframe_fdes_with_fres_v3): Use proper FRE type from
	FDE attributes when flipping FREs.

gas/testsuite/
	PR ld/33810
	* gas/cfi-sframe/cfi-sframe.exp (cfi-sframe-common-pr33810): Run
	new test.
	* gas/cfi-sframe/cfi-sframe-common-pr33810.d: New test.
	* gas/cfi-sframe/cfi-sframe-common-pr33810.s: Likewise.

Bug: https://sourceware.org/pr33810
Fixes: 8ab6e4c72ab6 ("[SFrame-V3] include: gas: libsframe: split FDE into idx and attr")
Reported-by: Alan Modra <amodra@gmail.com>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>