Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.Approved by: re (implicit)Sponsored by: The FreeBSD Foundation
Merge from vendor: libdtrace MD parts needed by fasttrap.Sponsored by: The FreeBSD Foundation
libdtrace MD dependent files. These interact with the fasttrap providerand so they are needed for constructing pid and usdt probes.