[PPC64] C2 crashes when accessing nonexisting jvms of CallLeafDirectNode

C2 crashes during build with the following stack:
#0 0x00003fffb617df6c in JVMState::depth (this=0x0) at /usr/work/d056149/openjdk/jdk/src/hotspot/share/opto/callnode.hpp:260
#1 0x00003fffb62e0850 in JVMState::same_calls_as (this=0x3fff4c18e180, that=0x0)
    at /usr/work/d056149/openjdk/jdk/src/hotspot/share/opto/callnode.cpp:307
#2 0x00003fffb6e7ae54 in NonSafepointEmitter::observe_safepoint (this=0x3fff6d8ca7f8, jvms=0x0, pc_offset=1600)
    at /usr/work/d056149/openjdk/jdk/src/hotspot/share/opto/output.cpp:1212
#3 0x00003fffb6e6ef04 in PhaseOutput::fill_buffer (this=0x3fff6d8cada8, cb=0x3fff6d8cadc8, blk_starts=0x3fff4c0e6df0)
    at /usr/work/d056149/openjdk/jdk/src/hotspot/share/opto/output.cpp:1564
#4 0x00003fffb6e69864 in PhaseOutput::Output (this=0x3fff6d8cada8) at /usr/work/d056149/openjdk/jdk/src/hotspot/share/opto/output.cpp:432

observe_safepoint() is called with jvms == NULL from fill_buffer with mach = CallLeafDirectNode. "_guaranteed_safepoint" needs to get set correctly for all MachCallNodes after JDK-8254231.

In addition MachCallRuntimeNode::ret_addr_offset() need update for the new assertion in output.cpp.