zygote: make all capabilities inheritable.

Set CapInh to the full set of permitted capabilities, so that the crash
handler can raise ambient capabilities to allow crash_dump to ptrace
zygote-descended children without needing CAP_SYS_PTRACE. CapInh is
restricted by filesystem capabilities if the ambient capability set
hasn't been raised, so this should only have an effect when ambient
capabilities are modified.

Bug: http://b/34853272
Test: debuggerd -b `pidof system_server`
Change-Id: I27d2aa4ab4fc47a183ce2b254be178de4d58840c