Use so.0 extension for shared libraries

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Change-Id: I7f0e29e0443154acc62206e3d35e54b892d34592
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/wayland/+/572524
Reviewed-by: David Reveman <reveman@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index 627c5fc..6cc5bce 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -139,6 +139,7 @@
 
 shared_library("wayland-client") {
   visibility = [ ":*" ]
+  output_extension = "so.0"
   sources = [ "src/wayland-client.c" ]
   deps = [ ":common_static" ]
   public_deps = [ ":client_headers" ]
@@ -147,6 +148,7 @@
 
 shared_library("wayland-server") {
   visibility = [ ":*" ]
+  output_extension = "so.0"
   sources = [ "src/wayland-server.c" ]
   deps = [ ":common_static" ]
   public_deps = [ ":server_headers" ]