Update version string to 0.9
In 49af9a90, pocl LLVM passes were unconditionally set to compile with
-DNDEBUG. This causes kernel compile time asserts when LLVM is compiled with
assertions enabled:
llvm/lib/IR/Value.cpp:534: void llvm::ValueHandleBase::AddToExistingUseList(llvm::ValueHandleBase**): Assertion `VP.getPointer() == Next->VP.getPointer() && "Added to wrong list?"' failed.

Since llvm-config cannot be relied to pass the correct NDEBUG setting, this commit
adds a configure-time check to find out the correct value.
Do not assign StringRef from a temporary. Silence valgrind.
Do not use aligned_alloc due to its size restriction (must be multiple of alignment).
Fix pocl.icd contents on *BSD (i.e. the encoding of library version to file name)
Update the correct lib prefix to the icd.
Merge branch 'release_0_9'

Conflicts:
	Makefile.am
	configure.ac