OSV-2021-1074 Use-of-uninitialized-value in SkBaseDevice::save

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=36647 Crash type: Use-of-uninitialized-value Crash state: SkBaseDevice::save SkCanvas::internalSave SkCanvas::internalSaveLayer...