8168503: JEP 297: Unified arm32/arm64 Port
Reviewed-by: kvn, enevill, ihse, dholmes, erikj, coleenp, cjplummer

8166560: [s390] Basic enablement of s390 port.
Summary: Also fix problem with ARM Elf configuration.
Reviewed-by: dholmes, coleenp

8067194: Restructure hotspot/agent/src to conform the modular source layout
Summary: Move sources under jdk.hotspot.agent
Reviewed-by: ihse, erikj, jbachorik