glws_glx: Allow pixel buffers in GlxDrawable::swapBuffers

Pixel buffers are allowed to be used in glXSwapBuffers.

glx 1.4 spec, 3.3.5 "Off Screen Rendering", "glXCreatePbuffer":

 "The resulting pbuffer will contain color buffers and ancillary
  buffers as specified by config. It is possible to create
  a pbuffer with back buffers and to swap the front and back
  buffers by calling glXSwapBuffers."

Fixes replaying of Blender traces.

Signed-off-by: Danylo Piliaiev <danylo.piliaiev@globallogic.com>
Change-Id: I8433f3c92e64a1acb32d045dd2857fefe588b488
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/apitrace/+/2224544
Reviewed-by: Po-Hsien Wang <pwang@chromium.org>
Commit-Queue: Robert Tarasov <tutankhamen@chromium.org>
Tested-by: Robert Tarasov <tutankhamen@chromium.org>
1 file changed