Replace calls to dup() with fcntl(F_DUPFD_CLOEXEC). The only difference
between the two is that O_CLOEXEC is set on the newly duped file
descriptor. This helps address file descriptor leaks crossing an exec()
boundary.
Test: compiles and boots
Change-Id: I95218331382b7a3432d31a46c173009dc4df1a6b
Hides getFd & getFileDescriptor due to lifecycle concenrs.
Adds ASharedMemory_dupFromJava to allow sharing a shared
memory region between Java & Native as safe as possible.
Mis-use results in an FD leak instead of double-close.
Bug: 64394076
Test: SharedMemory CTS tests
Change-Id: I01a5eb978fc4e99559a79baac75754c32f13bdc4