audio: use F_DUPFD_CLOEXEC to dup the MMAP buffer

Duplicate the MMAP shared memory buffer FD using F_DUPFD_CLOEXEC.
This was done to prevent clang-tidy errors.

These bugs were listed for historical reference.
Bug:  64311216
Bug: 134381208

This CL might fix this bug.
Bug: 148097400
Test: atest AAudioTests

Change-Id: I5e78109d03dc76ebaf9f82eafee3d39e5f763968