Use erase-remove idiom to remove dead SkSL functions.
Use erase-remove idiom to remove dead SkSL functions.

This pattern is a bit more efficient when multiple removals occur; it
avoids moving elements up more than once.
(https://en.wikipedia.org/wiki/Erase%E2%80%93remove_idiom)

Change-Id: I612d3c52145c889e30f7203f3c7298e461e855a5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/314459
Commit-Queue: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>
Commit-Queue: Brian Osman <794c0b5534edf5601d88e1d41975d0262da12894@google.com>
Auto-Submit: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>
Reviewed-by: Brian Osman <794c0b5534edf5601d88e1d41975d0262da12894@google.com>

aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia