remove support for non-lowercased $$eXpaNd() functions

we have been warning about such functions for a while now, now execute.
the qmake language is (generally) case-sensitive, so this wasn't all
that useful anyway.

Change-Id: I1388ac2d5a1104389aeb3347e739a0d5e69e138d
Reviewed-by: Qt Doc Bot <qt_docbot@qt-project.org>
Reviewed-by: Joerg Bornemann <joerg.bornemann@nokia.com>
(cherry picked from qtbase/b04192d94b9fb680f99ae38ff008919c0ad371ea)
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

src/shared/proparser/qmakebuiltins.cpp

@@ -396,15 +396,6 @@ ProStringList QMakeEvaluator::evaluateBuiltinExpand(
     traceMsg("calling built-in $$%s(%s)", dbgKey(func), dbgSepStrList(args));
 
     ExpandFunc func_t = ExpandFunc(statics.expands.value(func));
-    if (func_t == 0) {
-        const QString &fn = func.toQString(m_tmp1);
-        const QString &lfn = fn.toLower();
-        if (!fn.isSharedWith(lfn)) {
-            func_t = ExpandFunc(statics.expands.value(ProKey(lfn)));
-            if (func_t)
-                deprecationWarning(fL1S("Using uppercased builtin functions is deprecated."));
-        }
-    }
     switch (func_t) {
     case E_BASENAME:
     case E_DIRNAME: