stub out codegen of binary plus. We now compile:

if (11 + 42) {

to:

        %tmp = add i32 11, 42           ; <i32> [#uses=1]
        %tobool = icmp ne i32 %tmp, 0           ; <i1> [#uses=1]
        br i1 %tobool, label %ifthen, label %ifend


but this doesn't handle any of the interesting/hard stuff yet.

llvm-svn: 39545