Fixes the X86 Base template.

It turns out that using using TargetLowering::<member> causes problems when compiling with g++. The problem was fixed by using
Machine:: instead, where Machine is the template parameter. With name-dependent identifier, g++ does the right thing.

BUG= None
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/1208663002.