Avoid unneeded use of wxLocale in wxDateTime::Format()

On OS X, wxDateTime::Format() uses wxString::Replace() to
unconditionally replace locale-specific %c, %x and %X specifiers in the
format string if present. Doing so causes three wxLocale::GetInfo()
calls that are often not necessary.

Check for the presence of these  specifiers before calling GetInfo().

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78423 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/datetimefmt.cpp

@@ -316,9 +316,12 @@ wxString wxDateTime::Format(const wxString& formatp, const TimeZone& tz) const
 
     wxString format = formatp;
 #ifdef __WXOSX__
-    format.Replace("%c",wxLocale::GetInfo(wxLOCALE_DATE_TIME_FMT));
-    format.Replace("%x",wxLocale::GetInfo(wxLOCALE_SHORT_DATE_FMT));
-    format.Replace("%X",wxLocale::GetInfo(wxLOCALE_TIME_FMT));
+    if ( format.Contains("%c") )
+        format.Replace("%c", wxLocale::GetInfo(wxLOCALE_DATE_TIME_FMT));
+    if ( format.Contains("%x") )
+        format.Replace("%x", wxLocale::GetInfo(wxLOCALE_SHORT_DATE_FMT));
+    if ( format.Contains("%X") )
+        format.Replace("%X", wxLocale::GetInfo(wxLOCALE_TIME_FMT));
 #endif
     // we have to use our own implementation if the date is out of range of
     // strftime()