The llvm X86/Win64 code generator was generating 32-bit relative calls
when calling these special/intrinsic functions. It turns out that, under
Windows 8 (and 10), the DLL containing these functions is loaded more
than 2 GB away from our jitted code in the process virtual address space.
The MCJIT ELF symbol relocation couldn't do anything about it and that
lead to crashes.
The issue can be fixed by using indirect call via 64-bit register.
This patch includes updated regression tests.