Fix unused-but-set-variable totQuadsSeen
Fix unused-but-set-variable totQuadsSeen

In a Windows component release build with Chromium clang GrTextureOp.cpp
FillInVertices totQuadsSeen is calculated but never used. Put it behind
SkDEBUGCODE to match the other post condition asserts.

Change-Id: I6d26709caa952bdad8744ce5bdd82e11dbfa521e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/433437
Reviewed-by: Robert Phillips <95e8ac5504948c7bf91b22c16a8dbb7ae7c66bfd@google.com>
Commit-Queue: Ben Wagner <53965154ffeecc4a10886eab9259e95965f2979a@google.com>

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