QLocale: StringToDoubleConverter::StringToDouble() takes an int

The code already checks that "numLen" would fit in an int.

Change-Id: I592dee258f13211b5ac31990ab6058c3d2855f99
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/text/qlocale_tools.cpp

@@ -307,7 +307,7 @@ QSimpleParsedNumber<double> qt_asciiToDouble(const char *num, qsizetype numLen,
         // a number over 2 GB in length is silly, just assume it isn't valid
         return {};
     } else {
-        d = conv.StringToDouble(num, numLen, &processed);
+        d = conv.StringToDouble(num, int(numLen), &processed);
     }
 
     if (!qIsFinite(d)) {