Reland "Put the syscall header file in the modulemap."

This reverts commit f2dc75d08b131dd53b9f4b946cf67b6cb55dd65b.

Reason for revert: Updated with fix

Original change's description:
> Revert "Put the syscall header file in the modulemap."
>
> This reverts commit 38fa95c52142968d51681c747de9b3913b02e433.
>
> Reason for revert:
> LUCI Bisection has identified this change as the culprit of a build failure. See the analysis: https://ci.chromium.org/ui/p/chromium/bisection/compile-analysis/b/8702882351645789857
>
> Sample failed build: https://ci.chromium.org/b/8702882351645789857
>
> If this is a false positive, please report it at http://b.corp.google.com/createIssue?component=1199205&description=Analysis%3A+https%3A%2F%2Fchromium-review.googlesource.com%2Fc%2Fchromium%2Fsrc%2F%2B%2F6975305&format=PLAIN&priority=P3&title=Wrongly+blamed+https%3A%2F%2Fci.chromium.org%2Fui%2Fp%2Fchromium%2Fbisection%2Fcompile-analysis%2Fb%2F8702882351645789857&type=BUG
>
> Original change's description:
> > Put the syscall header file in the modulemap.
> >
> > This fixes https://ci.chromium.org/ui/p/chromium/builders/findit/gofindit-culprit-verification/84473/overview
> >
> > Bug: 435303825
> > Change-Id: I6a6a696450b2f5f4628a0b34747775db37215d55
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6975305
> > Auto-Submit: Matt Stark <msta@google.com>
> > Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
> > Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
> > Cr-Commit-Position: refs/heads/main@{#1519746}
> >
>
> Bug: 435303825
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Change-Id: Iffdad1242e8f41c0a2ac64050c7aeca9508e505e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6975003
> Commit-Queue: luci-bisection@appspot.gserviceaccount.com <luci-bisection@appspot.gserviceaccount.com>
> Bot-Commit: luci-bisection@appspot.gserviceaccount.com <luci-bisection@appspot.gserviceaccount.com>
> Owners-Override: luci-bisection@appspot.gserviceaccount.com <luci-bisection@appspot.gserviceaccount.com>
> Cr-Commit-Position: refs/heads/main@{#1519750}

Bug: 435303825
Change-Id: I62fef691e605f42ec446ecc92d1cde5dd899921d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6977893
Commit-Queue: Matt Stark <msta@google.com>
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Matthew Denton <mpdenton@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1521041}