Add per-file OWNERS for PPC-specific cctests

BUG=
R=jkummerow@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1259013002

Cr-Commit-Position: refs/heads/master@{#29901}

test/cctest/OWNERS

@@ -3,3 +3,8 @@ per-file *-mips*=gergely.kis@imgtec.com
 per-file *-mips*=akos.palfi@imgtec.com
 per-file *-mips*=balazs.kilvady@imgtec.com
 per-file *-mips*=dusan.milosavljevic@imgtec.com
+per-file *-ppc*=dstence@us.ibm.com
+per-file *-ppc*=joransiu@ca.ibm.com
+per-file *-ppc*=jyan@ca.ibm.com
+per-file *-ppc*=mbrandy@us.ibm.com
+per-file *-ppc*=michael_dawson@ca.ibm.com