There is possibility of someone dlclosing a library
while dl_iterate_phdr in progress which can lead to
dl_iterate_phdr calling callback with invalid address
if it was unmapped by dlclose.
Bug: http://b/22047255
Change-Id: I3fc0d9fd2c51fb36fd34cb035f37271fa893a7be
(cherry picked from commit f7d5bf334dc4bc5b7399d4c8268e1b0bf676548f)