Tweak printing of oom_adj to add a compressed format.

Now that the spacing of oom_adj output has gotten larger, it is
increasingly annoying to read when used as inline text.  So add
an option to print as a compact form that has no extra padding.

Bug: 123888618
Test: manual
Change-Id: Id91b510e3fee6acdc52237588179c0a64fbe1686