Add include guards to SkCodec.cpp depending on enabled codecs
Add include guards to SkCodec.cpp depending on enabled codecs

This means we don't have to have the JPEG headers around
even if we aren't building with JPEG enabled.

Change-Id: Icd6b3b88aef845511741ea77a0e8ce64ffd66f25
Bug: skia:12584
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/466765
Reviewed-by: Leon Scroggins <995cad867ca30d6399abe011583a53547c8afea1@google.com>

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