Revert "Omit dead SkSL functions"

This reverts commit 97fe0cbed26bebaa4814b94195da2308901a6219.

Reason for revert: ASAN failures

Original change's description:
> Omit dead SkSL functions
> 
> Now that SkSL inlines functions, dead functions are very common. This
> change causes them to be omitted from the final output.
> 
> Change-Id: Ie466a3f748812eff1a368498365c89d73ab0b7be
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/292684
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

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

Change-Id: Id20c5be67dd574d30d6f978ba610e43aa5018416
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/293241
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
9 files changed