New static flags system

This is a new static flag system, designed to have all flags in a central place, and compiled into the binary without requiring static constructors for registration.  All flags are moved out of the specific modules and into flags.defs, with different sections for debug, release, etc.  The flag variables are always defined.  For example, a debug flag in release mode still exists, but is read only and set to the default value.

[Dean McNamee, 2008-09-11 10:48:59]

I threw away all the dynamic flag stuff, it was too complicated.  This means
that we have a few testing flags in our v8 binaries, but we can work on removing
those later.

Hope you're prepared for the review of doom.

[Kasper Lund, 2008-09-11 13:55:42]

LGTM. I still think you should consider renaming the .defs file to something
else.

http://codereview.chromium.org/1935/diff/53/270
File src/flags.cc (right):

http://codereview.chromium.org/1935/diff/53/270#newcode50
Line 50: struct Flag {
I would make this a class since it has methods and everything.

http://codereview.chromium.org/1935/diff/53/270#newcode108
Line 108: case TYPE_BOOL:
The cases should be indented with two spaces.

http://codereview.chromium.org/1935/diff/53/270#newcode121
Line 121: return true;  // NOTREACHED
Remove comment and insert an UNREACHABLE() macro call before the return.

http://codereview.chromium.org/1935/diff/53/270#newcode127
Line 127: case TYPE_BOOL:
The cases should be indented with two spaces.

[lars.bak, 2008-09-11 14:11:46]

Hi Dean

Great first step to move all flags to one file.
However, it would be perfect if you could eliminate the flags.defs.

Otherwise, LGTM,
  Lars

http://codereview.chromium.org/1935/diff/53/271
File src/flags.defs (right):

http://codereview.chromium.org/1935/diff/53/271#newcode1
Line 1: // Copyright 2008 the V8 project authors. All rights reserved.
I understand the reason for the state based include but we should reduce flags
to be in release or in release+debug.
Since most flags is compiled away in release mode, I think this is OK. If you
make this change flags can be defined in ONE giant macro.
This will also eliminate the need for flags.def.

http://codereview.chromium.org/1935/diff/53/272
File src/flags.h (right):

http://codereview.chromium.org/1935/diff/53/272#newcode35
Line 35: #define FLAG_MODE_DECLARE
I don't like the defs file extension. Please use .h as extension. After all, it
is a C++ header file.