Suppress a partial-availability warning in process_reader_test.cc.
Suppress a partial-availability warning in process_reader_test.cc.

BUG=491157
R=rsesek@chromium.org

Review URL: https://codereview.chromium.org/1153763007

Patch from Erik Chen <erikchen@chromium.org>.

hankbao/Crashpad,atom/crashpad,Chilledheart/crashpad,Chilledheart/crashpad,atom/crashpad,hokein/crashpad,chromium/crashpad,Chilledheart/crashpad,hankbao/Crashpad,chromium/crashpad,hokein/crashpad,hokein/crashpad,atom/crashpad,hankbao/Crashpad,chromium/crashpad