ARM: boot: pass boot disk identifier

This to stop the vfs_boot.cpp code from complaining.
debugger/debuganalyzer: Remove the explicit -Werror from Jamfile

Specifying -Werror in the Jamfiles directly prevents the build
system from disabling error-on-warning for some arch specific
warnings (or even globally), breaking the ARM build.

The "src/apps" directory is already setup to compile with -Werror
by the build system anyway, so remove the explicit setting here.
ARM: stub out missing int64 atomic functions

Also, add an item to the TODO list for this. Really need to figure it out soon...