tests: Refine Bionic dlclose destruction test.

tests: Refine Bionic dlclose destruction test.

The purpose of this change is to test that C constructors and
destructors contained in shared libraries are properly called
when the corresponding libs are loaded and unloaded through
dlopen() and dlclose(), or when the program exits.

The test_dlclose_destruction test already performs this for
static C++ construction/destruction. The change refines it
with another shared library that uses __attribute__((constructor))
and __attribute__((destructor)) from C instead

(see the new libdlclosetest2 shared library).

A new test, test_executable_destructor is also added to check
that the constructor and destructor functions located in the
executable program itself are properly called.

Change-Id: If364d1c710282e8117f980b09490770e7d8d1e33