[8u] Request for approval: Backport of 8144487 and 8145754

[Tobias Hartmann]

Hi,

please approve and review the following backports to 8u.

8144487: PhaseIdealLoop::build_and_optimize() must restore major_progress flag if skip_loop_opts is true
https://bugs.openjdk.java.net/browse/JDK-8144487
http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/21689239c407

8145754: PhaseIdealLoop::is_scaled_iv_plus_offset() does not match AddI
https://bugs.openjdk.java.net/browse/JDK-8145754
http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/0e9d64117522

Nightly testing showed no problems and the changes apply cleanly to 8u-dev.

Thanks,
Tobias