Recently, ES3 specific getIntegerv queries were removed from ES2.
Unfortunately, GL_MAX_COLOR_ATTACHMENTS was moved to the ES3
section, but was still supposed to be in the ES2 section,
since the GL_EXT_draw_buffers exposes it.

Change-Id: I2272ccf282558e10ee6cfb1be9d124cc59df14fa
Reviewed-on: https://swiftshader-review.googlesource.com/9911Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>