utils: use /data/local/tmp as temprary dir on Android

[simpleton]

/tmp does not exist on Android and cannot be created by regular applications.
Use /data/local/tmp as an alternate tmpDir.

Test Plan

before

Test bfptrace on Android device. bpftrace raises runtime_error due to the /tmp is not available and creatable.

$ ./bpftrace  -e 't:timer:hrtimer_start { @[ksym(args->function)] = count(); }'
terminating with uncaught exception of type std::runtime_error: creating temporary path for kheaders.tar.xz failed
Aborted

after

runtime_error got migrated.

$ bpftrace  -e 't:timer:hrtimer_start { @[ksym(args->function)] = count(); }'
Attaching 1 probe...
[..]

[danobi]

Please add a CHANGELOG entry (see https://github.com/iovisor/bpftrace/blob/master/docs/developers.md#changelog) but lgtm otherwise

[tnovak]

FYI bpftrace will use the TMPDIR env variable if it exists, which is normally[*] set to /data/local/tmp on Android:

$ adb shell echo \$TMPDIR
/data/local/tmp

[*] It's set by adbd here, so this applies to adb shell but may not if, say, invoking bpftrace from another process or clearing the environment.