liblzma/rangecoder: Exclude x32 from the x86-64 optimisation.

[sebastianas]

The x32 port has a x86-64 ABI in term of all registers but uses only 32bit pointer like x86-32. The assembly optimisation fails to compile on x32. Given the state of x32 I suggest to exclude it from the optimisation rather than trying to fix it.

Pull request type

Please check the type of change your PR introduces:

• [X] Bugfix

What is the current behavior?

https://buildd.debian.org/status/fetch.php?pkg=xz-utils&arch=x32&ver=5.5.2beta-1&stamp=1708036388&raw=0

In file included from ../../../../src/liblzma/lzma/lzma_decoder.c:17:
In function ‘lzma_decode’,
    inlined from ‘lzma_decode’ at ../../../../src/liblzma/lzma/lzma_decoder.c:235:1:
../../../../src/liblzma/rangecoder/range_decoder.h:644:9: error: invalid 'asm': operand is not a condition code, invalid operand code 'c'
  644 |         __asm__( \
      |         ^~~~~~~
../../../../src/liblzma/rangecoder/range_decoder.h:671:9: note: in expansion of macro ‘rc_asm_bittree_n’
  671 |         rc_asm_bittree_n(probs_base_var, final_add, \
      |         ^~~~~~~~~~~~~~~~
../../../../src/liblzma/lzma/lzma_decoder.c:75:17: note: in expansion of macro ‘rc_bittree3’
   75 |                 rc_bittree3(ld.low[pos_state], \
      |                 ^~~~~~~~~~~
../../../../src/liblzma/lzma/lzma_decoder.c:421:25: note: in expansion of macro ‘len_decode_fast’
  421 |                         len_decode_fast(len, coder->match_len_decoder,
      |                         ^~~~~~~~~~~~~~~
../../../../src/liblzma/rangecoder/range_decoder.h:644:9: error: invalid 'asm': operand is not a condition code, invalid operand code 'c'
…

Does this introduce a breaking change?

• [ ] Yes
• [X] No

[JiaT75]

Omitting assembly from x86-32 is certainly much simpler than trying to adapt for it. Thanks for the PR! This is merged in master as e9053c907250c70d98b319d95fa54cb94fc76869.