Add heap usage of SkSL::Compiler to nanobench output

This will let us track a new metric that measures the heap usage of
constructing a default compiler object. I anticipate adding similar
stats about the heap usage from compiling simple vs. complex SkSL.

Change-Id: Idb814c0b5d210d00a06ce5dc7147437aabcba1bb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/301359
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
5 files changed