Check GL_EXT_texture_format_BGRA8888 before GL_APPLE_texture_format_BGRA8888
Check GL_EXT_texture_format_BGRA8888 before GL_APPLE_texture_format_BGRA8888

When both GL_EXT_texture_format_BGRA8888 and GL_APPLE_texture_format_BGRA8888
extensions are present, the presence of GL_APPLE_texture_format_BGRA8888 was
preventing GL_EXT_texture_format_BGRA8888 from allowing BGRA8888 to be used
as a render target. By checking for GL_EXT_texture_format_BGRA8888 first,
this solves the issue.

The issue was encountered trying to run vr_pixeltests on top of SwiftShader
on the bots with a version of SwiftShader exposing both extension strings.

Change-Id: I446ec502a4703d24c24339708dcbbe9c334a7533
Reviewed-on: https://skia-review.googlesource.com/114495
Reviewed-by: Brian Salomon <61fabaaf0876044aeedfd8e351e485c028d69e7b@google.com>
Commit-Queue: Alexis Hetu <1c7141772178a7e80858c3db5052b328076f08f4@google.com>

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