Revert "Guard pipewire configs with rtc_use_pipewire."

This reverts commit 4e8a797.

Reason for revert: Required to revert CL causing compile problems that prevent rolling into chrome.
See
https://ci.chromium.org/p/chromium/builders/try/cast_shell_linux/726007
https://chromium-review.googlesource.com/c/chromium/src/+/2461647

Original change's description:
> 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 <mbonadei@webrtc.org>
> Reviewed-by: Tommi <tommi@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#32345}

TBR=mbonadei@webrtc.org,tommi@webrtc.org,grulja@gmail.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:682122
Change-Id: Ifc493c0789520b6aa163390c382b6aaff9d732a8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/187353
Reviewed-by: Guido Urdaneta <guidou@webrtc.org>
Commit-Queue: Guido Urdaneta <guidou@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32364}

Author: Guido Urdaneta

modules/desktop_capture/BUILD.gn

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