Use build flag to safeguard virtual_camera service access

... in CameraProviderManager.

Bug: 318088136
Bug: 301023410
Test: locally enabling / disabling RELEASE_PACKAGE_VIRTUAL_CAMERA and
rebuilding
Test: atest CameraProviderManagerTest

Change-Id: I275fa268ea67365b968821112a9200e6cdb9fd5d
diff --git a/services/camera/libcameraservice/Android.bp b/services/camera/libcameraservice/Android.bp
index 575e0fb..5b76bb0 100644
--- a/services/camera/libcameraservice/Android.bp
+++ b/services/camera/libcameraservice/Android.bp
@@ -112,6 +112,7 @@
         "libcameraservice_device_independent",
         "libdynamic_depth",
         "libprocessinfoservice_aidl",
+        "libvirtualdevicebuildflags",
         "media_permission-aidl-cpp",
     ],
 }