hwservicemanager: read random bytes from /dev/urandom

On some device such as emualtor, reading frm /dev/random will
block and cause hwservicemanger to hang.

This CL reads random bytes from /dev/urandom instead, just like
vold does.

BUG: 37084577

Test: build sdk_gphone_x86 target and lunch emualtor.
Change-Id: I9faa3b0356bb25f66a6686c5a5c3ff37a191a0f9
(cherry picked from commit 0c5aba7ab8f2e5e2bda49ec5719d2db213b0e127)
1 file changed