BUILD: tools: include auxv a bit later

As reported in https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=24745,
haproxy fails to build with TARGET=generic and without extra options due
to auxv.h not being included, since the __GLIBC__ macro is not yet defined.
Let's include it after other libc headers so that the __GLIBC__ definition
is known. Thanks to David and Tim for the diag.

This should be backported to 2.2.
1 file changed