Problems with 82e79c63642c, NOT_CONSTANT with sigfillset()

There is a problem with the somewhat new commit 82e79c63642c introducing NOT_CONSTANT with sigfillset():

Compiling on older (?) MacOs machine leads to this:
     Undefined symbols for architecture x86_64:
       "_false_but_the_compiler_does_not_know_it_", referenced from:
           _start_command in libgit.a(run-command.o)

What is the best thing to avoid this ?

The introduced "false_but_the_compiler_does_not_know_it" triggers here because there is a proper prototype in signal.h and then a #define sigfillset() ... further down in the file, which can never fail.

a) Define a sigfillset_or_die_if_needed macro,
   which does what we have today, and is simply defined
   as sigfillset() without any error checking for MacOs(some version)
b) Revert the commit (and fix the conflicts)
c) Anything better ?

I have a raw patch for b), not fully cooked, as the commit message is the hardest part. Before sending that out: Are the thoughts about a better solution ?