Guard pipewire configs with rtc_use_pipewire.

[1] has introduced two dependencies on
//modules/desktop_capture:pipewire_config
even when rtc_use_pipewire=false, this CL changes the guard in order to
make sure GN doesn't raise errors when is_linux=true and
rtc_use_pipewire=false.

[1] - https://webrtc-review.googlesource.com/c/src/+/160649

No-Try: True
Bug: chromium:682122
Change-Id: I28d2f10936dd75199a2a98862751708eb1e5615a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/187122
Commit-Queue: Mirko Bonadei <[email protected]>
Reviewed-by: Tommi <[email protected]>
Cr-Commit-Position: refs/heads/master@{#32345}

Author: MirkoBonadei

modules/desktop_capture/BUILD.gn

@@ -76,19 +76,17 @@ if (rtc_include_tests) {
         "window_finder_unittest.cc",
       ]
       public_configs = [ ":x11_config" ]
-      if (is_linux) {
+      if (rtc_use_pipewire) {
         public_configs += [ ":pipewire_config" ]
-        if (rtc_use_pipewire) {
-          configs += [
-            ":pipewire_config",
-            ":gio",
-          ]
-
-          if (rtc_link_pipewire) {
-            configs += [ ":pipewire" ]
-          } else {
-            deps += [ ":pipewire_stubs" ]
-          }
+        configs += [
+          ":pipewire_config",
+          ":gio",
+        ]
+
+        if (rtc_link_pipewire) {
+          configs += [ ":pipewire" ]
+        } else {
+          deps += [ ":pipewire_stubs" ]
         }
       }
       if (is_win) {
@@ -147,19 +145,17 @@ if (rtc_include_tests) {
       }
       deps += [ ":desktop_capture_mock" ]
       public_configs = [ ":x11_config" ]
-      if (is_linux) {
+      if (rtc_use_pipewire) {
         public_configs += [ ":pipewire_config" ]
-        if (rtc_use_pipewire) {
-          configs += [
-            ":pipewire_config",
-            ":gio",
-          ]
-
-          if (rtc_link_pipewire) {
-            configs += [ ":pipewire" ]
-          } else {
-            deps += [ ":pipewire_stubs" ]
-          }
+        configs += [
+          ":pipewire_config",
+          ":gio",
+        ]
+
+        if (rtc_link_pipewire) {
+          configs += [ ":pipewire" ]
+        } else {
+          deps += [ ":pipewire_stubs" ]
         }
       }
     }