Add vm.overrides property in pipewire and pulse-server

Apply vm.override properties when running in a VM. Increase the
default quantum to 1024 when running in a VM to cause less
dropouts.

src/daemon/pipewire-pulse.conf.in

@@ -43,6 +43,10 @@ context.modules = [
 	    #pulse.min.quantum = 256/48000          # 5ms
 	    #pulse.default.format = F32
 	    #pulse.default.position = [ FL FR ]
+            # These overrides are only applied when running in a vm.
+            vm.overrides = {
+	        pulse.min.quantum = 1024/48000         # 22ms
+            }
         }
     }
 ]

src/daemon/pipewire.conf.in

@@ -25,6 +25,11 @@ context.properties = {
     #default.video.height      = 480
     #default.video.rate.num    = 25
     #default.video.rate.denom  = 1
+    #
+    # These overrides are only applied when running in a vm.
+    vm.overrides = {
+        default.clock.min-quantum     = 1024
+    }
 }
 
 context.spa-libs = {