TableGen/CodeEmitterGen.cpp: Fix an expression of generating bitmask.
TableGen/CodeEmitterGen.cpp: Fix an expression of generating bitmask.

~0U might be i32 on 32-bit hosts, then (uint64_t)~0U might not be expected as (i64)0xFFFFFFFF_FFFFFFFF, but as (i64)0x00000000_FFFFFFFF.

git-svn-id: a4a6f32337ebd29ad4763b423022f00f68d1c7b7@152407 91177308-0d34-0410-b5e6-96231b3b80d8

lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx