Revert "C++: Fix highlighting for lines with predefined macros"

This takes too much memory. For qtcreator.pro the numbers are as
follows:

    Patch applied:  ~ 1600MB (RES)
    Patch reverted: ~  510MB (RES)

This reverts commit 4c2daa90ce.

Task-number: QTCREATORBUG-10973
Change-Id: I843bd7c1ea4a26a1ec55ddc14c2a34a98d040922
Reviewed-by: hjk <hjk121@nokiamail.com>
Reviewed-by: Robert Loehning <robert.loehning@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/plugins/cpptools/cppfindreferences.cpp

@@ -558,8 +558,6 @@ restart_search:
         usages.clear();
         foreach (const Document::MacroUse &use, doc->macroUses()) {
             const Macro &useMacro = use.macro();
-            if (useMacro.isPredefined())
-                continue;
 
             if (useMacro.fileName() == macro.fileName()) { // Check if this is a match, but possibly against an outdated document.
                 if (source.isEmpty())