roll: third_party/pigweed: pw_spi_linux: Remove linkage specification from cli main

According to the C++ standard, the main function shall not be declared
with a linkage-specification. An upcoming Crosstool release includes
[20-1706 [Clang] Strengthen checks for `main`  to meet
`[basic.start.main]p3`’s requirements (#101853)](http://go/compilers/37ec6e5f12afe4a37872bf28f280423696f39019),
which will lead to breakages when compiling `extern "C" int main...`.

This CL removes the linkage specification from pw_spi_linux_cli's main
function and moves the main function to the global namespace.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/230291

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 7654e112c63755f..704a5f3dde6a006
Roller-URL: https://ci.chromium.org/b/8739402105364386625
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I3b00062e06ead0765cdeb13d11df9be08d0d5c92
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/230452
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 7654e11..704a5f3 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 7654e112c63755f93c7b59e2fb7ab31a84bcb8fe
+Subproject commit 704a5f3dde6a006418cbf01a3b9a67e6957f1164