The .byte directive will be used instead of .incbin since the latter
comes with complications involving build-time dependency detection.

Drive-by-edits: Move macro definitions closer to their use-sites.

TBR=rmcilroy@chromium.org

Cq-Include-Trybots: luci.v8.try:v8_win64_msvc_compile_rel;master.tryserver.chromium.linux:linux_chromium_rel_ng
Bug: v8:6666
Change-Id: Ibda0b3577688248dbf627cb69965d28309193859
Reviewed-on: https://chromium-review.googlesource.com/906488
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51147}