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/clangbackendclangipc-source.pri

@@ -29,10 +29,12 @@ HEADERS += \
     $$PWD/clangreparsesupportivetranslationunitjob.h \
     $$PWD/clangrequestdocumentannotationsjob.h \
     $$PWD/clangrequestreferencesjob.h \
+    $$PWD/clangrequesttooltipjob.h \
     $$PWD/clangresumedocumentjob.h \
     $$PWD/clangstring.h \
     $$PWD/clangsupportivetranslationunitinitializer.h \
     $$PWD/clangsuspenddocumentjob.h \
+    $$PWD/clangtooltipinfocollector.h \
     $$PWD/clangtranslationunit.h \
     $$PWD/clangtranslationunits.h \
     $$PWD/clangtranslationunitupdater.h \
@@ -86,8 +88,10 @@ SOURCES += \
     $$PWD/clangreparsesupportivetranslationunitjob.cpp \
     $$PWD/clangrequestdocumentannotationsjob.cpp \
     $$PWD/clangrequestreferencesjob.cpp \
+    $$PWD/clangrequesttooltipjob.cpp \
     $$PWD/clangsuspenddocumentjob.cpp  \
     $$PWD/clangsupportivetranslationunitinitializer.cpp \
+    $$PWD/clangtooltipinfocollector.cpp \
     $$PWD/clangtranslationunit.cpp \
     $$PWD/clangtranslationunits.cpp \
     $$PWD/clangtranslationunitupdater.cpp \