Pull in r357362 from upstream clang trunk (by David Chisnall):

[objc-gnustep] Use .init_array not .ctors when requested.

This doesn't make a difference most of the time but FreeBSD/ARM
doesn't run anything in the .ctors array.

This should help with updating the libobjc2 port for armv7.

Requested by: theraven
Upstream PR: https://github.com/gnustep/libobjc2/issues/83
MFC after: 3 days