Added -q flag to showmap.

dumpstate calls showmap for each pid, and since most of them are empty,
it ends up polluting logcat with entries like:

03-17 14:49:05.974 12160 12160 E dumpstate: command '/system/xbin/su
root showmap -q 9867' failed: No such file or directory

BUG: 26906985
Change-Id: I7e064b2ec8901b6ccee49b228be96ff2847c703c