MAKEFILE: Add support for building under Haiku

Find the header and library paths with findpaths.

We need -lnetwork for sockets.

We do support pthread, it's in libroot.

We do support dlopen, it's in libroot.
Work around missing nice() on Haiku
Haiku has socklen_t
VAX, PDP11: Fix VHD support to save the correct updated part of the Block Allocation Table (BAT) when new blocks are added to a VHD.
VAX780: Added idle support for SysVR2

A new idle mode (SYSV) is now available:

    sim> SET CPU IDLE=SYSV
WINDOWS-BUILD: Fix to properly get/generate the .git-commit-id file on a newly cloned repo
VAX: Simplified idle detection which allows more operating systems to properly detect when they are idling.

Removed the recently added SET CPU IDLE=SYSV since any SET CPU IDLE command will work for SysV.  Existing configurations probably did a SET CPU IDLE=32V which works fine now.

Changed things based on the realization that ANY branch instruction which tests memory and then branches to itself is an idle loop if the branch is taken.  This is without regard to address space, access mode, If interrupts are disabled, then it is a hung system and the simulation should halt.
VAX: Fix the PxBR and SBR validation tests to correctly reflect the 780 microcode patch 38 from Bob Supnik

This fix allows older Unix operating systems to once again run with the VAX 780 simulator.
WINDOWS_BUILD: Added the ability to cleanly start generating windows builds from a new local platform.