fix CSharpTemp.TestDestructors

TestDestructors test cannot be run twice as a static variable holds data from
the first run.

Add an init function to set the static variable to a known state.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@iki.fi>
CppParser: remove unnecessary #includes

Use forward declarations to avoid the need to include lots of clang headers.

This drops the compilation time for CppParser from 17.8 seconds to 14.1 seconds
for me.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@iki.fi>
Merge pull request #258 from tomba/remove-includes

CppParser: remove unnecessary #includes
Merge pull request #255 from tomba/fix-warnings

Fix trivial warnings
Merge pull request #257 from tomba/fix-test

fix CSharpTemp.TestDestructors
fix