master c14eab2: Fix dumping on GNU/Linux ppc64le

[Eivind Fonn]

Hello,

This commit seems to break the build on Windows, at
least our appveyor CI, see for example

https://ci.appveyor.com/project/tarsius/libegit2/builds/20225833/job/uio10kqtx44kwf6w

The function maybe_disable_address_randomization
is declared with two different signatures, failing when
the void version is used because the return value is
assigned.

Eivind