Replace incorrect uses of wxString::empty() with the intended clear().

empty() doesn't empty the string but just checks for its emptiness, clear()
was supposed to be used here instead.

Thanks to PVS-Studio for finding these problems.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70750 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/translation.cpp

@@ -986,7 +986,7 @@ bool wxMsgCatalogFile::LoadData(const DataBuffer& data,
                 if ( m_charset == wxS("CHARSET") )
                 {
                     // "CHARSET" is not valid charset, but lazy translator
-                    m_charset.empty();
+                    m_charset.clear();
                 }
             }
         }

src/msw/registry.cpp

@@ -326,7 +326,7 @@ void wxRegKey::SetHkey(WXHKEY hKey)
   m_mode = Write;
 
   // reset old data
-  m_strKey.empty();
+  m_strKey.clear();
   m_dwLastError = 0;
 }