Fix build for LLVM >= r74640 Some LLVM objects now take a 'Context' to make multi-threaded apps easier. Since we're not multi-threaded it's safe to use llvm::getGlobalContext() which gives us the same behavior as we had before.

[Environment]

DFLAGS=-I%@P%/../lphobos -I%@P%/../import -L-L%@P%/../lib
# -R%@P%/../lib