[SkQP/Android] Replace -Weverything with -Wextra

-Weverything is not recommended, use -Wextra.

CQ_INCLUDE_TRYBOTS=skia.primary:Build-Debian9-Clang-x86-devrel-Android_SKQP,Test-Debian9-Clang-NUC7i5BNK-CPU-Emulator-x86-devrel-All-Android_SKQP

Bug: b/143713277
Test: mma
Change-Id: Ibaca86bd52348d544a8109b25ae013001444935d
Reviewd-on: https://android-review.googlesource.com/1163299
Cherry-pick: 29cd4eca88df5fafde51ee9a50e3deb96263fc64
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/253956
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
2 files changed