Unlock the graphics buffer before queuing it.
Unlock the graphics buffer before queuing it.

The buffer changes ownership after queuing it, so unlock it first.
The decRef() gets removed in a subsequent patch.

Bug b/34981145

Change-Id: I4710699af46a7cbde12e97bc444ad35747509b07
Reviewed-on: https://swiftshader-review.googlesource.com/8848
Reviewed-by: Greg Hartman <1491e78df1ea2169b62fa2ceaf1a32538792aab8@google.com>
Reviewed-by: Nicolas Capens <0612353e1fcebbfd4b302d9337447ca0cdfa9122@google.com>
Tested-by: Greg Hartman <1491e78df1ea2169b62fa2ceaf1a32538792aab8@google.com>

bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader