Revert "restrict SHARED to linux_64"

This reverts commit 374144af8817a188dceeea1a44b437e5caa3b1ac.

[Bugzilla 9722](http://d.puremagic.com/issues/show_bug.cgi?id=9722) was fixed by https://github.com/D-Programming-Language/dmd/issues/1752