[cmake] Check for Haiku when setting LIB_NAMES for GNU ld

Haiku uses GNU ld for linking, but is not captured in the
conditional when setting LIB_NAMES. This causes a shared
library with no symbols on Haiku. This patch simply adds
a check for whether the CMake system name is Haiku in
addition to the existing checks.

Patch by Jérôme Duval.

Differential Revision: https://reviews.llvm.org/D34998

llvm-svn: 307607