Fix caching of HLSL in D3D backend
Fix caching of HLSL in D3D backend

We were always tagging the stored shaders as SkSL, so they (naturally)
didn't compile when we loaded them.

Change-Id: I96062808751b6233c9e90b29150f66270d0dd198
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/296836
Commit-Queue: Brian Osman <794c0b5534edf5601d88e1d41975d0262da12894@google.com>
Commit-Queue: Greg Daniel <39df0a804564ccb6cf75f18db79653821f37c1c5@google.com>
Auto-Submit: Brian Osman <794c0b5534edf5601d88e1d41975d0262da12894@google.com>
Reviewed-by: Greg Daniel <39df0a804564ccb6cf75f18db79653821f37c1c5@google.com>

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