8142502: [TESTBUG] Exclude runtime/ErrorHandling/SecondaryErrorTest.java on OSX until JDK-8139300 has been resolved Reviewed-by: hseigel, mseledtsov, minqi

8140689: Skip last young-only gc if nothing to do in the mixed gc phase Reviewed-by: mgerdin, drwhite

8138740: Start initial mark right after mixed GC if needed Summary: Instead of issuing a single young-only GC after the end of all mixed GCs, if needed immediately start an initial mark in that young-only GC. Reviewed-by: drwhite, mgerdin

8139874: After G1 Full GC, the next GC is always a young-only GC Summary: Allow initiation of an initial mark after Full GC Reviewed-by: ehelin

8140597: Forcing an initial mark causes G1 to abort mixed collections Summary: Postpone the initial mark request until the current mixed GC phase has finished. Reviewed-by: mgerdin

8140584: nmethod::oops_do_marking_epilogue always runs verification code Reviewed-by: tschatzl, kvn

8141654: Tests missing -XX:+UnlockDiagnosticVMOptions Summary: Add missing unlock options. Reviewed-by: brutisso, tschatzl

Merge