Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.Approved by: re (implicit)Sponsored by: The FreeBSD Foundation
Copy head to stable/9 as part of 9.0-RELEASE release cycle.Approved by: re (implicit)
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.