Migrate INFINITY_ to the shared Transform header.

Additionally, Clang and GCC have a builtin which can generate an
infinity without needing to bit-pun via a union.

Change-Id: Id7f30075949b85fc02da4bf1055bee58e1f75b3b
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/773463
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
3 files changed