On Android, set $ENV{TMPDIR} on the tests for open($fh, undef)

This is primarily to get the tests working. open($fh, undef) calls
PerlIO_tmpfile(), which requires either /tmp to exist or $ENV{TMPDIR}
to be set.  In Android, neither of those is true.

A possible fix would be to have PerlIO_tmpfile() behave like File::Temp
and just try the cwd; the "real" fix would require calling java
at startup to get Context.getCacheDir.
t/op/getpid.t: Silence undef warnings if getconf doesn't exist.

If a platform has getppid() but not getconf and we're building a
threaded perl, this file would've shown undef warnings, although
no tests were affected.
t/op/threads-dirh.t: Only test telldir and seekdir if they are available
t/op/exec.t: Skip a test under -DUSE_SHELL_ALWAYS
t/lib/warnings/9uninit: Skip two tests under -DUSE_SHELL_ALWAYS
t/io/pipe.t: Skip test under -DUSE_SHELL_ALWAYS
t/porting/: Skips for cross-compilation
lib/ExtUtils/t/Embed.t: Skip tests is cross-compiling and $Config{cc} is not available
dist/IO/t/io_pipe.t: Work around android only having an inbuilt echo
Net::Ping: Handle getprotobyn{ame,umber} not being available
IO::Socket::INET: Handle getprotobyn{ame,umber} not being available
dist/ExtUtils-Install: Skip tests if make is not available
ext/File-Glob/t/basic.t: On android, remove .stdout files from glob()'s results
ext/POSIX/t/time.t: Conditionalize the use of setlocale/LC_TIME

On Android, all locales are simply disabled, which broke the assumption
that LC_TIME is always available.
ext/POSIX/t/sysconf.t: Skip testing pathconf with _PC_LINK_MAX on android
ext/IPC-Open3/t/IPC-Open3.t: TODO a test under -DUSE_SHELL_ALWAYS
Skip the VMS tests if not on VMS
cpan/Sys-Syslog/Syslog.pm: Conditionalize the use of setlocale/LC_TIME
Net::Domain: Stop domainname() from giving out warnings in android
Perl::OStype: Report Android as a Unix-like OS.