Revert "use sizeof(expr) for unevaluated syntax check"

Using sizeof(expr) can trigger a compile-time error,
"lambda expressions are not allowed in an unevaluated context", when passing
expression containing lambda, like a std algorithm. This error is considered
a standard defect, as it is meant to prevent lambdas in decltype
or templates, but not in sizeof.

This reverts commit 227598af47.

include/internal/catch_common.h

@@ -119,8 +119,9 @@ namespace Catch {
     std::ostream& operator << ( std::ostream& os, SourceLineInfo const& info );
 
     // This is just here to avoid compiler warnings with macro constants and boolean literals
-    inline bool alwaysTrue( std::size_t = 0 ) { return true; }
-    inline bool alwaysFalse( std::size_t = 0 ) { return false; }
+    inline bool isTrue( bool value ){ return value; }
+    inline bool alwaysTrue() { return true; }
+    inline bool alwaysFalse() { return false; }
 
     void throwLogicError( std::string const& message, SourceLineInfo const& locationInfo );