The spec for glDeleteVertexArrays states that "Unused names in arrays
are silently ignored, as is the value zero."

b/116699321

Change-Id: I7cca0336dd9841b360f8fa20f6c0ac9677ec3ce1
Reviewed-on: https://swiftshader-review.googlesource.com/21048Reviewed-by: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>