Update gdb bitmap viewer.
Update gdb bitmap viewer.

This updates the gdb bitmap viewer for color enums, SkBitmap layout, and
to work with gdb when using python 2.

Change-Id: Id50048ecd7db5b3febaff15f118d8b8183c7dbf1
Reviewed-on: https://skia-review.googlesource.com/136247
Reviewed-by: Herb Derby <9e12a3d2bbf73546e47cc9958f6ba8f3215b7eaf@google.com>
Commit-Queue: Ben Wagner <53965154ffeecc4a10886eab9259e95965f2979a@google.com>

rubenvb/skia,rubenvb/skia,google/skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,google/skia,rubenvb/skia,google/skia,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,google/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,HalCanary/skia-hc,google/skia,google/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,rubenvb/skia,HalCanary/skia-hc,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,HalCanary/skia-hc,aosp-mirror/platform_external_skia,HalCanary/skia-hc,HalCanary/skia-hc,aosp-mirror/platform_external_skia,rubenvb/skia,google/skia,Hikari-no-Tenshi/android_external_skia