Charlie Jacobsen authored Jun 18, 2014 and Vikram Narayanan committed Oct 25, 2016

Set up new header files, under include/lcd-domains/
-- lcd-domains.h: main include, contains struct lcd
-- ipc.h: struct lcd_ipc_regs, for message registers

Updated virt/lcd/lcd-domains.c to use new headers.

Updated arch-dep code to use new struct lcd_ipc_regs.
struct lcd_arch contains a pointer to the allocated
page for stack / ipc registers. struct lcd (arch-indep)
contains a pointer to the same memory (so that the
arch-indep code can access the ipc regs directly if
it wishes).

Message registers should be accessed through arch-dep
macros (to be implemented next) for portability and
speed (some of the message registers will be
implemented using machine regs, so the message registers
in struct lcd_ipc_regs are `shadows').

Message register design based on seL4. See seL4 manual,
4.1.