Macros are now inaccessible from CSA except if their declaration is
marked with the "export" keyword. The implicit field accessors for class
fields are always exported.

In this CL, unwarranted access from CSA is prevented by appending a
pseudo-random suffix to non-exported names. This is to be replaced by
something more principled, namely by not including these macros at all in
the headers included from CSA.

Bug: v8:7793
Change-Id: I3ffb2e91a616623f81b4b4508e001ad0cf65d2c2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1615258
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Simon Zünd <szuend@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61672}