Clang: Provide tooltips

This includes also the query data for the help system (F1) for an
identifier under cursor.

Regressions (libclang changes necessary):
 - Function signatures do not contain default values.
 - Aliases are not resolved for/at:
   - template types
   - qualified name of a type

Fixes/Improvements:
 - Resolve "auto"
 - On a template type, show also the template parameter.
 - For a typedef like
     typedef long long superlong;
   the tooltip was "long long superlong", which was confusing.
   Now, "long long" is shown.

New:
 - Show first or \brief paragraph of a documentation comment.
 - Show size of a class at definition.
 - Show size of a field member in class definition.

Task-number: QTCREATORBUG-11259
Change-Id: Ie1a07930d0e882015d07dc43e35bb81a685cdeb8
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/tools/clangbackend/source/clangtranslationunit.cpp

@@ -27,6 +27,7 @@
 
 #include "clangbackend_global.h"
 #include "clangreferencescollector.h"
+#include "clangtooltipinfocollector.h"
 #include "clangtranslationunitupdater.h"
 #include "clangfollowsymbol.h"
 #include "clangfollowsymboljob.h"
@@ -139,6 +140,20 @@ void TranslationUnit::extractDocumentAnnotations(
     skippedSourceRanges = this->skippedSourceRanges().toSourceRangeContainers();
 }
 
+
+ToolTipInfo TranslationUnit::tooltip(UnsavedFiles &unsavedFiles,
+                                     const Utf8String &textCodecName,
+                                     uint line,
+                                     uint column) const
+{
+    return collectToolTipInfo(unsavedFiles,
+                              textCodecName,
+                              filePath(),
+                              m_cxTranslationUnit,
+                              line,
+                              column);
+}
+
 ReferencesResult TranslationUnit::references(uint line, uint column, bool localReferences) const
 {
     return collectReferences(m_cxTranslationUnit, line, column, localReferences);