More robust OSL_LLVM_VERSION regex to work with 3-part version numbers
Split ShaderGlobals definition into separate shaderglobals.h
Guard point transforms against possible division by 0
Create a LLVM_Util class (in llvm_util.{h,cpp}) that handles ALL direct calls
to LLVM APIs, and has NO special knowledge of OSL or its internals.

BackendLLVM (which is intimately tied to OSL) now is built on top of
LLVM_Util. Neither BackendLLVM nor the rest of liboslexec needs to directly
touch LLVM API calls and don't even need to include a single llvm header.

LLVM_Util has no dependencies on anything else in OSL (though does want
TypeDesc and ustring), and could be used as a standalone library from
other apps, to vastly simplify using LLVM to dynamically JIT code and
then execute it.  An example of this can be found in llvmutil_test.cpp.
Enable Boost Wave as the pre-processor for SPI builds
Dead code and declaration removal
Add RendererServices pointer directly to ShaderGlobals for easier access
Better handling of OpenEXR libs naming based on version (auto-discover 2.1 and above from config header file).