RFR: JDK-8177957 run-test summary lines look bad/misleading with long test names

[Magnus Ihse Bursie]

When running individual tests using run-test, the summary section gets 
hard to read. For instance: (imagine having a fixed-with font :))
    TEST TOTAL PASS FAIL ERROR
    jtreg:hotspot/test/gc/stress/gcbasher/TestGCBasherWithG1.java 1 1 0 0

What makes this exact example even worse is that it aligns so bad so 
that the "1" belonging to the TOTAL column, ends up aligned with the 
FAIL label, so it looks as if the test failed.

If the test name is too long to fit before the number columns, we should 
add a line break, so the numbers still align on the right columns, but 
on the line after.

This bug also fixes some remaining issues from JDK-8191820:
* jtreg test descriptors are now normalized to TOPDIR (or CUSTOM_ROOT, 
if present). (Without this fix, almost all test names were too long.)
* Do not disallow running named test groups for jtreg tests out-of-tree.
* And a simplification in the matching for paths (we didn't need to 
treat absolute paths differently).

Bug: https://bugs.openjdk.java.net/browse/JDK-8177957
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8177957-linebreak-long-test-names/webrev.01

/Magnus