Fix uses of the OFFSET macro
Fix uses of the OFFSET macro

The OFFSET macro requires an offset provided in terms of class member
offset, without any function call included, because it relies on an
offset from the beginning of the class, without creating any object.
The vec<T, 4>::operator[] was getting invoked on a null object to
compute the offset in some cases, which is equivalent to using the
"v" member of the vec<T, 4> class, so the code was modified to use
the "v" member rather than relying on the vec<T, 4>::operator[].

This was causing compilation errors when building a new SwiftShader
repo on a Linux cloud instance.

Bug: b/247127895
Change-Id: I861d15e1b636b077485b6617bc256b347a7eb144
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/68268
Presubmit-Ready: Alexis Hétu <1c7141772178a7e80858c3db5052b328076f08f4@google.com>
Commit-Queue: Alexis Hétu <1c7141772178a7e80858c3db5052b328076f08f4@google.com>
Kokoro-Result: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Antonio Maiorano <86d87a6550afb6b07035c9743fa181900589f7e0@google.com>
Tested-by: Alexis Hétu <1c7141772178a7e80858c3db5052b328076f08f4@google.com>

google/swiftshader,google/swiftshader,google/swiftshader