common: Improve/fix spir-v utils This change improves the handling of macroed-sections of the code. Also, fixed some typos. Bug: angleproject:370557215 Change-Id: I437b8c4d835dada4554569c72ef7100568c6be48 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5898609 Commit-Queue: Austin Annestrand <a.annestrand@samsung.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>