Get one Perfetto unittest working on Windows

This change disables most source files from building on Windows and
makes enough adjustments to what remains so that they will build, in
order to give a starting point for a strategy of gradually getting more
code building and running on Windows.

There are probably more source files which could be easily made to work
on Windows but the goal of this change is just to get one test class
working, which is TimeTest, which passes.

This change also adds a test which crudely validates that GetWallTimeNs
and GetThreadCPUTimeNs work.

Testing this on Windows in Chromium requires applying the following
patch to BUILD.gn:

@@ -656,7 +656,7 @@ group("gn_all") {
     }
   }

-  if (is_mac || is_linux || is_android) {
+  if (is_mac || is_linux || is_android || is_win) {
     deps += [ "//third_party/perfetto:all" ]
   }

Bug: 78878306

Change-Id: I692582afea63685c6c73b68b788183489de5c9c2
diff --git a/BUILD.gn b/BUILD.gn
index 7e3dcc0..d7ce8bc 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -57,9 +57,14 @@
     "gn:default_deps",
     "gn:gtest_main",
     "src/base:unittests",
-    "src/protozero:unittests",
-    "src/tracing:unittests",
   ]
+  # TODO(brucedawson): Enable these for Windows when possible.
+  if (!is_win) {
+    deps += [
+      "src/protozero:unittests",
+      "src/tracing:unittests",
+    ]
+  }
   if (!build_with_chromium) {
     deps += [
       "src/ftrace_reader:unittests",