Cherry-pick 7.11 changes to 8.2

Cherry-picked commits:
    c64829b2: Fallback to open if multifs_open fails.
    21770732: Fix gdbserver process interruption.
    b711aa82: Add Unix domain socket support to gdbserver 7.9.1.
    35ee6839: Remove gdb hack.
    78af0f6f: Handle cross compile for locale configuration
    a7e49fd0: bfd: add experimental support for SHT_RELR sections.
    689b53da: Fix debugging of stripped PIE executables with padded PT_TLS

Fixed transport_is_reliable variable in b711aa82 so that it is consistent
with 8.2 changes.

Bug:62547070
Change-Id: I14a6b819cc0590dc11853dbce91111adfe2cb489