Without this the GN shared library doesn't export any of the gl
entry-points making it useless.

Bug swiftshader:86

Change-Id: I97f6acf4204d6e908ad12c89c79d40769dc824a4
Reviewed-on: https://swiftshader-review.googlesource.com/13308Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>