Rewrite bit counting functions

Get rid of macros and use templates instead,
this is safer and allows us fix the warning:

ISO C++ forbids braced-groups within expressions

That broke compilation with -pedantic flag under
gcc and POPCNT enabled.

No functional and no performance change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/misc.cpp

@@ -146,7 +146,7 @@ void dbg_print_mean(ofstream& logFile) {
 
 const string engine_name() {
 
-  const string cpu64(CpuHas64BitPath ? " 64bit" : "");
+  const string cpu64(CpuIs64Bit ? " 64bit" : "");
 
   if (!EngineVersion.empty())
       return AppName + " " + EngineVersion + cpu64;