On Android, set TMPDIR before calling configure

On Android, set TMPDIR before calling configure

The full explanation for this is here:
http://stackoverflow.com/questions/15283220/android-shell-eof

In short, Android's sh has a bug in that writing

cat <<EOF
...
EOF

will try creating a temporary file in /sqlite_stmt_journals,
which may or may not exist, and may or may not be writeable
by the current user.
So instead do the right thing and set TMPDIR to whatever the
current File::Spec->tmpdir returns.