Refactor: Simplify boolean expressions in llvm Support

[LegalizeAdulthood]

Summary

Simplify boolean expressions using true and false with clang-tidy

[dblaikie]

Looks good - committed in r233004

lib/Support/APFloat.cpp

 APFloat::addOrSubtractSignificand(const APFloat &rhs, bool subtract)
 {
   integerPart carry;
   lostFraction lost_fraction;
   int bits;
 
   /* Determine if the operation on the absolute values is effectively
      an addition or subtraction.  */
-  subtract ^= (sign ^ rhs.sign) ? true : false;
+  subtract ^= (sign ^ rhs.sign) != 0;
 
   /* Are we bigger exponent-wise than the RHS?  */
   bits = exponent - rhs.exponent;
 
   /* Subtraction is more subtle than one might naively expect.  */
   if (subtract) {
     APFloat temp_rhs(rhs);
     bool reverse;