Register __llvm_profile_write_file with at_quick_exit

Bug: http://b/186576313

This allows programs to call quick_exit() to avoid static destructors
but still be able to write coverage data.

This is a workaround until we add at_quick_exit to libclang_rt.profile.

Test: Change dex2oat to call quick_exit instead of _exit and verify that
      coverage data gets written.
Change-Id: Iaaa438a4c999ca9506b9b2f9dbfd2ef37808aa16
1 file changed