Build failure with glibc 2.34 or higher: SIGSTKSZ is no longer constant

[nathanielhourt]

When building against glibc 2.34, a build failure occurs rooted here due to the fact that SIGSTKSZ is no longer a constexpr value (see glibc changelog). There is also an error about a type mismatch in the arguments to max, but the 'interesting' error is the constexpr trouble.

This seems to be a trivial fix, as it appears that nothing depends on stack_cutoff being constexpr. Simply replace line 273 with:

std::size_t stack_cutoff = std::max<long>(252144, SIGSTKSZ);