If an image has a single mip level, and filtering isn't LOD dependent,
as is the case when using FILTER_MIN_POINT_MAG_LINEAR or
FILTER_MIN_LINEAR_MAG_POINT, LOD computation is not necessary in
order to perform image sampling and can be bypassed entirely.

Bug: b/179889245
Change-Id: Ic69fe0c45211ccbb66c88c502c2dba1c50630aa7
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/52688
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Commit-Queue: Alexis Hétu <sugoi@google.com>