40.0.2
40.0.2

Changes:
 * Add libffi workaround for building against newer LLVMs configured
   with `ENABLE_LIBFFI`.
 * Correct type of second parameter to LLVMOrcGetSymbolAddress
 * Fix incorrect name for LLVMGetAttributesAtIndex (was missing 's')

tari/llvm-sys.rs,tari/llvm-sys.rs,tari/llvm-sys.rs