re-enabling and massaging code.

R=rsc
APPROVED=rsc
DELTA=2496  (1880 added, 330 deleted, 286 changed)
OCL=33487
CL=33504

R=rsc
APPROVED=rsc
DELTA=84  (68 added, 4 deleted, 12 changed)
OCL=33493
CL=33499

R=rsc
APPROVED=rsc
DELTA=35  (30 added, 4 deleted, 1 changed)
OCL=33491
CL=33498

R=rsc
DELTA=263  (0 added, 263 deleted, 0 changed)
OCL=33466
CL=33485

- removed defs.go (moved declarations into arith.go where they belong)

R=r
DELTA=40  (16 added, 20 deleted, 4 changed)
OCL=33464
CL=33464

- implememted empty stubs for 386 assembly routines
- removed assembly code operating on single words (except for one)
- adjusted tests

R=rsc
DELTA=126  (46 added, 67 deleted, 13 changed)
OCL=33461
CL=33461

- changed Cmp to return -1, 0, +1
- added corresponding test cases

R=rsc
DELTA=173  (136 added, 3 deleted, 34 changed)
OCL=33431
CL=33459

R=rsc
APPROVED=rsc
DELTA=61  (61 added, 0 deleted, 0 changed)
OCL=33438
CL=33454

R=rsc
APPROVED=rsc
DELTA=35  (2 added, 1 deleted, 32 changed)
OCL=33436
CL=33453

R=rsc
APPROVED=rsc
DELTA=6  (0 added, 0 deleted, 6 changed)
OCL=33434
CL=33452

Since pres != nil was already checked and the routine sets *pres to false
and returns, the subsequent tests are unneeded.

R=rsc
APPROVED=rsc
DELTA=4  (0 added, 4 deleted, 0 changed)
OCL=33439
CL=33441

R=rsc
APPROVED=rsc
DELTA=204  (204 added, 0 deleted, 0 changed)
OCL=33437
CL=33440

does so in ways that permit its size to be known.

R=rsc
DELTA=35  (35 added, 0 deleted, 0 changed)
OCL=33427
CL=33433

bug165.go:13:6: error: invalid recursive type 'S'

This is a different line from the 6g error message, which is
"invalid map key type".  I accomodated both compilers by
merging the line.

bug188.go:13:2: error: unexpected reference to package

I made the error message less specific, which I think is fine
here.

R=rsc
DELTA=2  (0 added, 0 deleted, 2 changed)
OCL=33398
CL=33426

R=rsc
OCL=33418
CL=33418

R=rsc,r
DELTA=5  (3 added, 0 deleted, 2 changed)
OCL=33413
CL=33417

R=rsc
DELTA=41  (20 added, 2 deleted, 19 changed)
OCL=33412
CL=33415

R=rsc
OCL=33407
CL=33409

R=rsc
DELTA=6  (4 added, 2 deleted, 0 changed)
OCL=33400
CL=33400

R=rsc
OCL=33382
CL=33391

interface type in a struct.  It is meaningful and the
compilers support it.

R=gri
DELTA=2  (0 added, 0 deleted, 2 changed)
OCL=33378
CL=33384

R=rsc
APPROVED=rsc
DELTA=286  (217 added, 42 deleted, 27 changed)
OCL=33319
CL=33383

- no other changes

R=r
DELTA=1248  (623 added, 623 deleted, 2 changed)
OCL=33371
CL=33371

- renamed Z -> Int
- made Int ops methods on *Int
- "install" assembly routines dynamically
- replace mulVW functions with mulAddVWW
  of equivalent performance but symmetric functionality
  to divWVW
- implemented scanN

status:
- need mulNN (trivial)
- need division/modulo after which the set of
  elementary operations is complete
- to/from string conversion working

R=rsc
DELTA=320  (124 added, 50 deleted, 146 changed)
OCL=33308
CL=33341

semacquire might move to another m.

R=r
DELTA=5  (2 added, 2 deleted, 1 changed)
OCL=33317
CL=33326

- remove language on (in-)complete types

DELTA=95  (8 added, 62 deleted, 25 changed)
OCL=33310
CL=33322

R=rsc,r
DELTA=16  (16 added, 0 deleted, 0 changed)
OCL=33292
CL=33303

R=rsc
DELTA=70  (16 added, 52 deleted, 2 changed)
OCL=33295
CL=33299

signal.

R=rsc
APPROVED=rsc
DELTA=1  (1 added, 0 deleted, 0 changed)
OCL=33249
CL=33296

R=rsc
APPROVED=rsc
DELTA=1  (0 added, 0 deleted, 1 changed)
OCL=33294
CL=33294

stacks produced by whole-package compilation.

Fix some off-by-ones in PC/line table parsing.  Hopefully.

R=rsc
APPROVED=rsc
DELTA=42  (24 added, 6 deleted, 12 changed)
OCL=33250
CL=33293

now 15% overhead instead of 30% in binaries.

R=ken
OCL=33235
CL=33288

- implemented low-level operations on word vectors
- implemented corresponding amd64 assembly routines for word vector operations
- implemented first set of operations on unsigned integers
- implemented first set of operations on signed integers
- implemented systematic test cases  for each data type

R=rsc
DELTA=1330  (1330 added, 0 deleted, 0 changed)
OCL=33132
CL=33285

at PC, to deal with functions that end with a CALL
instruction.  Special case known call-by-return functions.

R=rsc
APPROVED=rsc
DELTA=12  (6 added, 6 deleted, 0 changed)
OCL=33255
CL=33279

R=rsc
OCL=33273
CL=33276

R=r
DELTA=49  (0 added, 14 deleted, 35 changed)
OCL=33272
CL=33272

R=rsc
DELTA=2339  (19 added, 2303 deleted, 17 changed)
OCL=33239
CL=33253

R=rsc
APPROVED=rsc
DELTA=9  (4 added, 3 deleted, 2 changed)
OCL=33238
CL=33251

backtraces don't work,
but they didn't work when i started either.

R=ken
OCL=33230
CL=33230

R=rsc
APPROVED=rsc
DELTA=1  (0 added, 0 deleted, 1 changed)
OCL=33209
CL=33227