Run-tests: Fix/implement --update; avoid stdout patching.

The update has never worked reliably, but with the separation
of the `sed` and `diff` it is getting much better now.

Avoid stdout patching to improve --update mode further.
The tests still have stdout that differs based on flags.
Support those by having multiple (full) expected files.

Test: test.py -r --all-target --all-jvmti --all-prebuild \
              -t 1931 -t 1932 -t 1936 -t 1950 -t 1953 \
              -t 1954 -t 1955 -t 1956 -t 1969 -t 909
Change-Id: I070037717f9964755492b42b6efd52179deb4125
36 files changed