Break GN targets apart by library

Break GN targets apart by library

Make 4 distinct groups: vp8, vp9, vpx_dsp, and everything else. GN does
not allow overlapping basenames. Currently the assembly files processed
by yasm are still dumped into the base directory so we need to be
careful about those. But this frees up the different codecs to use the
same basename in the different codecs: though there may be differences
between the quantize in vp8 and in vp9, it's very valuable to be able to
put them each in the file names quantize.c

For many parts we only need to worry about the first three: those are
the only ones which will receive optimizations and thus the only which
we need to break out target-specific setup.

The assembly needs to be broken out for all 4 because emms.asm is a
legacy feature that needs to be included somewhere. We pray it may be
removed some day when mmx support is deprecated.

R=tomfinegan@chromium.org

Committed: https://chromium.googlesource.com/chromium/deps/libvpx/+/0f4f3fef4657930a0dc5ac2ec056f567b544e5c7

[Johann, 2015-08-05 22:42:12]

tested on x86. give it an eyeball and see what you think. i tried to test arm
but i couldn't find any instruction on setting up the GN build for arm. it looks
reasonable-ish to be, i think it's safe to commit here and run trybots in a
roll.

[Tom Finegan, 2015-08-05 22:57:32]

lgtm % optional nit and observation

Seems good enough for cq/roll bot run.

https://codereview.chromium.org/1272583003/diff/1/BUILD.gn
File BUILD.gn (right):

https://codereview.chromium.org/1272583003/diff/1/BUILD.gn#newcode74
BUILD.gn:74: }
The existing stuff seems to always add a blank line after closing braces at this
and global scope. Doesn't seem to effect readability either way. Up to you.

https://codereview.chromium.org/1272583003/diff/1/BUILD.gn#newcode82
BUILD.gn:82: defines = [ "CHROMIUM" ]
This being repeated in all targets seems weird, but I don't know scoping rules
in GN... And I'm not sure if it breaks things for this to be set globally (like
os_category, for ex).

[Johann, 2015-08-05 23:02:29]

https://codereview.chromium.org/1272583003/diff/1/BUILD.gn
File BUILD.gn (right):

https://codereview.chromium.org/1272583003/diff/1/BUILD.gn#newcode74
BUILD.gn:74: }
On 2015/08/05 22:57:32, Tom Finegan wrote:
> The existing stuff seems to always add a blank line after closing braces at
this
> and global scope. Doesn't seem to effect readability either way. Up to you.

I left these together specifically because they're almost identical versions of
the same rule

https://codereview.chromium.org/1272583003/diff/1/BUILD.gn#newcode82
BUILD.gn:82: defines = [ "CHROMIUM" ]
On 2015/08/05 22:57:32, Tom Finegan wrote:
> This being repeated in all targets seems weird, but I don't know scoping rules
> in GN... And I'm not sure if it breaks things for this to be set globally
(like
> os_category, for ex).

I have no idea which defines etc are required, so I did the lazy think and
copied all of them. If it was easier to test I would look at other options but
...

[Johann, 2015-08-05 23:02:46]

Committed patchset #1 (id:1) manually as
0f4f3fef4657930a0dc5ac2ec056f567b544e5c7 (presubmit successful).