crash_dump: fix overflow.

`1 << 32` overflows, resulting in bogus PR_CAP_AMBIENT_RAISE attempts,
and breaking dumping for processes with capabilities in the top 32 bits.

Bug: http://b/35241370
Test: debuggerd -b `pidof com.android.bluetooth`
Change-Id: I29c45a8bd36bdeb3492c9f74599993c139821088
1 file changed