Fix platform-specific header dependencies to be more precise

Make the GN conditionals match what happens in sources, or the other way around. Include headers only when they're used.

Bug: None
Change-Id: Ib8e3346e3c24eaa7e61ac4776dcd66efe2cc5c65
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/144880
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Commit-Queue: Oleh Prypin <oprypin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28500}
diff --git a/modules/audio_processing/BUILD.gn b/modules/audio_processing/BUILD.gn
index 81dc2be..488099a 100644
--- a/modules/audio_processing/BUILD.gn
+++ b/modules/audio_processing/BUILD.gn
@@ -302,7 +302,9 @@
 
 rtc_source_set("audio_processing_c") {
   visibility = [ ":*" ]  # Only targets in this file can depend on this.
-  sources = []
+  sources = [
+    "ns/windows_private.h",
+  ]
 
   if (rtc_prefer_fixed_point) {
     sources += [
@@ -324,7 +326,6 @@
       "ns/noise_suppression.h",
       "ns/ns_core.c",
       "ns/ns_core.h",
-      "ns/windows_private.h",
     ]
   }