Copy stable/10@r272459 to releng/10.1 as part ofthe 10.1-RELEASE process.Approved by: re (implicit)Sponsored by: The FreeBSD Foundation
Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.Approved by: re (implicit)Sponsored by: The FreeBSD Foundation
Eliminate gdb_checkc member from GDB_DBGPORT(), it is never used.Use polling behaviour for gdb_getc() where convenient, this edges uscloser to the console code.
Start each of the license/copyright comments with /*-, minor shuffle of lines
Add support for uart(4) being a debug port for the GDB backend.