ananas: Add shared library support

The Ananas Operating System (https://github.com/zhmu/ananas) has shared
library support as of commit 57739c0b6ece56dd4872aedf30264ed4b9412c77.

This change adds the necessary settings to clang so that shared
executables and libraries can be build correctly.

Submitted by:	Rink Springer
Differential Revision:	https://reviews.llvm.org/D41500

llvm-svn: 322064