bug#39164: 27.0.60; Intermittent crash on MacOS 10.14 in setup_process_coding_systems

[Robert Pluim]

>>>>> On Fri, 17 Jan 2020 23:01:10 +0200, Eli Zaretskii <eliz@gnu.org> said:

    Eli> Thanks, but the backtraces don't show any source information, and it
    Eli> is very hard to do anything about this without that.  Can you tell
    Eli> where in coding.c is setup_process_coding_systems + 152?

Iʼm on 10.14, and donʼt see this crash. Assuming my emacs-27 build is
similar to Justin's, itʼs this:

7988      setup_coding_system (coding_system, proc_decode_coding_system[inch]);
   0x000000010019645f <+143>:   mov    (%r12,%r15,8),%rsi
   0x0000000100196463 <+147>:   callq  0x10007b610 <setup_coding_system>

7989
7990      if (!proc_encode_coding_system[outch])
   0x0000000100196468 <+152>:   lea    0x4d3061(%rip),%r15        # 0x1006694d0
   0x000000010019646f <+159>:   mov    (%r15,%r14,8),%rsi
   0x0000000100196473 <+163>:   test   %rsi,%rsi
   0x0000000100196476 <+166>:   jne    0x100196489 
<setup_process_coding_systems+185>