Fix entering the kernel debugger when MULTIPROCESSOR is enabled; the
arguments to alpha_debug() were getting clobbered by the call to
cpu_pause_resume_all(), but they need to be passed along to ddb_t

Fix entering the kernel debugger when MULTIPROCESSOR is enabled; the
arguments to alpha_debug() were getting clobbered by the call to
cpu_pause_resume_all(), but they need to be passed along to ddb_trap().

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Don't try and symbol set debug_stack_top from the common symbol
debug_stack_bottom. It's bogus and disallowed in new binutils.

Remove clause 3 and 4 from TNF licenses

Make sure to include opt_foo.h if a defflag option FOO is used.

Don't use NBPG.

add missing #include "opt_kgdb.h"

Glue in KGDB. Needs some more work -- KGDB currently renders
DDB disabled, but it's a start.

Add experimental code for pausing other CPUs upon a CPU's
entry into the debugger. While I'm here, add splsched()
as per spl(9).

Whitespace police.

Fix a harmless typo.

Convert to traceback-friendly temporary labels.

Calculate what sp would have been and save it in otherwise-unused
FRAME_SP slot if entering ddb.

Add a common debugger entry point, alpha_debug(), which performs various
tasks (i.e. switches to the debug stack) and then invokes the appropriate
debugger (DDB or eventually KGDB).