182dbdf0f4 util: Detect posix_fallocate() instead of assuming (Vasil Dimov)
Pull request description:
Don't assume that `posix_fallocate()` is available on Linux and not
available on other operating systems. At least FreeBSD has it and we
are not using it.
Properly check whether `posix_fallocate()` is present and use it if it
is.
ACKs for top commit:
laanwj:
ACK 182dbdf0f4
Tree-SHA512: f9ed4bd661f33ff6b2b1150591e860b3c1f44e12b87c35e870d06a7013c4e841ed2bf17b41ad6b18fe471b0b23a4b5e42cf1400637180888e0bc56c254fe0766