CppLocatorFilter: Fix highlighting in extra info column

Given the following example:

  typedef int value;
  void value_test(void) {}
  void test(value v) {}

searching for "value" findes both candidates; and
for the locator filters "m" and "." highlighting
already worked fine.

For the locator filter ":", however, the arguments
are displayed in the extraInfo column. To get proper
highlighting here, we have to repeat the regexp match
in this column.

While fixing that, make sure that full-qualified
searches (separated by "::") are still highlighted
properly.

For the Clang Code Model, there is still a bug not
addressed by this patch:

 Ctrl+K with ". value" -> "value" isn't highlighted yellow.

Change-Id: Idd5eeeedb893151cd5c7f70f6b11397db788b706
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/cpptools/cpplocatorfilter.cpp

@@ -108,7 +108,12 @@ QList<Core::LocatorFilterEntry> CppLocatorFilter::matchesFor(
                     matchOffset = 0;
                 }
                 filterEntry.highlightInfo = highlightInfo(match);
-                if (matchOffset > 0) {
+                if (matchInParameterList && filterEntry.highlightInfo.starts.isEmpty()) {
+                    match = regexp.match(filterEntry.extraInfo);
+                    filterEntry.highlightInfo = highlightInfo(match);
+                    filterEntry.highlightInfo.dataType =
+                            Core::LocatorFilterEntry::HighlightInfo::ExtraInfo;
+                } else if (matchOffset > 0) {
                     for (int &start : filterEntry.highlightInfo.starts)
                         start -= matchOffset;
                 }