PR gcov-profile/7970
PR gcov-profile/16855
PR gcov-profile/44779
* g++.dg/gcov/pr16855.C: New test.
* coverage.c (build_gcov_exit_decl): New function.
(coverage_obj_init): Call the function and generate __gcov_exit
destructor.
* doc/gcov.texi: Document when __gcov_exit function is called.
* libgcov-driver.c (__gcov_init): Do not register a atexit
handler.
(__gcov_exit): Rename from gcov_exit.
* libgcov.h (__gcov_exit): Declare.
From-SVN: r240529
