OpenOCD actually checks this initial value now, and there's no reason
for it to indicate error.

https://github.com/riscv/riscv-isa-manual/commit/285c81746fe664060b62ae0584865dbfa9f42e1a

Configure should fail if device-tree-compiler is not installed

Fixes #107

Disable -Werror when building

This has a tendency to blow up on other platforms.

https://github.com/riscv/riscv-isa-manual/commit/326bec83de23f4d2daf24cfed6b5251748cad632

 - https://github.com/riscv/riscv-tools/issues/69

Updates to match the latest debug spec

Fix builds with "--enable-commitlog"