Provide a simpler and safer version of qdtoa()

The new version returns a QString instead of a char * that has to be
manually free()'d by the user. Also, it does away with most of the
parameters so that we can replace the implementation with something
saner without mapping all those modes between the implementations.

Change-Id: I42ff95648e7955b9e74eb0f459a1fdedc1ad7efb
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qlocale_tools.cpp

@@ -2614,4 +2614,14 @@ static char *_qdtoa( NEEDS_VOLATILE double d, int mode, int ndigits, int *decpt,
     return s0;
 }
 
+QString qdtoa(qreal d, int *decpt, int *sign)
+{
+    char *result = 0;
+    char *constResult = 0;
+    constResult = qdtoa(d, 0, 0, decpt, sign, 0, &result);
+    const QString ret(QString::fromLatin1(result ? result : constResult));
+    free(result);
+    return ret;
+}
+
 QT_END_NAMESPACE

src/corelib/tools/qlocale_tools_p.h

@@ -68,6 +68,7 @@ QT_BEGIN_NAMESPACE
 
 QString qulltoa(qulonglong l, int base, const QChar _zero);
 QString qlltoa(qlonglong l, int base, const QChar zero);
+Q_CORE_EXPORT QString qdtoa(qreal d, int *decpt, int *sign);
 
 enum PrecisionMode {
     PMDecimalDigits =             0x01,