Revert "Reland "Remove GrProgramDesc::KeyHeader structure""

This reverts commit 202420e0147b02f963de761a903b2c430dfa0cec.

Reason for revert: MSVC build failures

Original change's description:
> Reland "Remove GrProgramDesc::KeyHeader structure"
>
> This is a reland of 4bcd58afbf1a1993e453231c575b47a0ae1ec24d
>
> Original change's description:
> > Remove GrProgramDesc::KeyHeader structure
> >
> > Instead, just fold all of this information into the key, like everything
> > else. The only value that was accessed elsewhere is the initial key
> > length. That doesn't need to be part of the key, so store it separately
> > in the GrProgramDesc.
> >
> > Removing this special case logic is just the first step in revising how
> > we assemble keys.
> >
> > Bug: skia:11372
> > Change-Id: I52eb76812045e1906797cb37e809cfd0b3332ef0
> > Reviewed-on: https://skia-review.googlesource.com/c/skia/+/376797
> > Reviewed-by: Brian Salomon <bsalomon@google.com>
> > Commit-Queue: Brian Osman <brianosman@google.com>
>
> Bug: skia:11372
> Change-Id: I2cdb49aee3537e54dad9af1f9b47cf1aed1aca21
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/376849
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Brian Osman <brianosman@google.com>

TBR=bsalomon@google.com,robertphillips@google.com,brianosman@google.com

Change-Id: I0f4a76fa5d38d516554eed642eb9ab5f3222d9f3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:11372
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/377231
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
2 files changed