fixed bug in Ungetch() which was preventing wxExecute() from working: this method must clear the EOF flag!

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@16144 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/stream.cpp

@@ -763,22 +763,27 @@ size_t wxInputStream::GetWBack(void *buf, size_t bsize)
 
 size_t wxInputStream::Ungetch(const void *buf, size_t bufsize)
 {
+    if ( m_lasterror != wxSTREAM_NO_ERROR && m_lasterror != wxSTREAM_EOF )
+    {
+        // can't operate on this stream until the error is cleared
+        return 0;
+    }
+
     char *ptrback = AllocSpaceWBack(bufsize);
     if (!ptrback)
         return 0;
 
+    // Eof() shouldn't return TRUE any longer
+    if ( m_lasterror == wxSTREAM_EOF )
+        m_lasterror = wxSTREAM_NO_ERROR;
+
     memcpy(ptrback, buf, bufsize);
     return bufsize;
 }
 
 bool wxInputStream::Ungetch(char c)
 {
-    void *ptrback = AllocSpaceWBack(1);
-    if (!ptrback)
-        return FALSE;
-
-    *(char *)ptrback = c;
-    return TRUE;
+    return Ungetch(&c, sizeof(char)) != 0;
 }
 
 char wxInputStream::GetC()