It is no longer used now that profiling support at the Subzero level
is eliminated.

This change adjusts all of the uses of getSrc() on intrinsics to obtain
the correct operand, but does not yet make simplifications based on
having them align with load/store instructions.

Bug: b/179497998
Change-Id: I93705eaa1b7626184f612ab3a9755048004e531f
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/52529
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>