The `PRINT_EACH_PROCESSED_INSTRUCTION` preprocessor flag can control printing of each instruction before they are processed.
This is exceptionally helpful when debugging the debugger (or anything else to do with SpirvShader).

Bug: b/145351270
Change-Id: Iddfbedbfc86487d71f6980b2f3fb74f7f13e972f
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/40093Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>