Prevent the IPC layer from being included in builds it can't compile on.

Windows and Fushsia do not support the unix sockets used by the IPC
layer in perfetto. This was breaking the roll when chromium attempted
to build unittests for these sockets on those platforms.
see https://chromium-review.googlesource.com/c/chromium/src/+/1573670

Change-Id: If1fcb5420e2cf1a4b64e8259d6b6c137943d319a
diff --git a/gn/perfetto.gni b/gn/perfetto.gni
index 05bbba2..9c62f42 100644
--- a/gn/perfetto.gni
+++ b/gn/perfetto.gni
@@ -109,6 +109,10 @@
 
 # Only perfetto itself (standalone or with android) and chromium should link
 # in the IPC layer.
+#
+# This includes building things that rely on POSIX sockets, this places
+# limitations on the supported operating systems.
 perfetto_build_with_ipc_layer =
-    perfetto_build_standalone || perfetto_build_with_android ||
-    build_with_chromium
+    (is_android || is_linux || is_mac) &&
+    (perfetto_build_standalone || perfetto_build_with_android ||
+     build_with_chromium)