Refactor EvaluateScalarValueToBool out of if statement emission, so it can

be shared.

Implement infrastructure for unary operator emission.

Implement basic logical not support.  We now compile:

  register short X;

  if (!X) {

into:

        %tmp = load i16* %X             ; <i16> [#uses=1]
        %tobool = icmp ne i16 %tmp, 0           ; <i1> [#uses=1]
        %lnot = xor i1 %tobool, true            ; <i1> [#uses=1]
        zext i1 %lnot to i32            ; <i32>:0 [#uses=1]
        %tobool1 = icmp ne i32 %0, 0            ; <i1> [#uses=1]
        br i1 %tobool1, label %ifthen, label %ifend

llvm-svn: 39559