skcms: Increase transform op capacity and add bounds checks

Complex color transforms (e.g. A2B to B2A with 4-channel curve tables,
matrices, format and space conversion) can require ~40 ops, which
exceeded the previous hardcoded limit of 32 ops and resulted in a
stack buffer overflow.

Increase SKCMS_MAX_PROGRAM_OPS to 64, providing ample padding while
keeping stack overhead small. Harden add_op and add_op_ctx to avoid
writing past the program buffer during compilation, and add runtime
checks in both skcms_Transform and run_program to gracefully reject
programs that exceed the maximum capacity.

This limit is only hit when doing an A2B to B2A conversion, which
Chromium and Android do not do.

Fixed: b/530238257
TAG=agy
CONV=56f173c3-5496-4fd5-ad6b-34aebcff742d
Change-Id: I1868e43405dcd109c01c007ee0ade4d0aebe3198
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/1351256
Reviewed-by: Florin Malita <fmalita@google.com>
Commit-Queue: Christopher Cameron <ccameron@google.com>