I based this off of the API already create for llvm.dbg.value since both
intrinsics have the same arguments at the API level.
I added some tests exercising the API a little as well as an additional small
test that shows how one can use llvm.dbg.addr to limit the PC range where an
address value is available in the debugger. This is done by calling
llvm.dbg.value with undef and the same metadata info as one used to create the