SDL_net: cmake: use already-existing SDL2test when building with vendored SDL2

SDL Commits
1 
From de8e29615c5a7ae70493159b0dd2e29f868b810f Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Sat, 23 Jul 2022 16:48:51 +0200
Subject: [PATCH] cmake: use already-existing SDL2test when building with
 vendored SDL2

---
 CMakeLists.txt | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 769bb9d..fb6e6ca 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -22,7 +22,13 @@ project(SDL2_net
     VERSION "${FULL_VERSION}"
 )
 
-find_package(SDL2test)
+message(STATUS "Configuring ${PROJECT_NAME} ${PROJECT_VERSION}")
+
+if(TARGET SDL2::SDL2test)
+    set(SDL2test_FOUND ON)
+else()
+    find_package(SDL2test)
+endif()
 
 # Set defaults preventing destination file conflicts
 set(SDL2NET_DEBUG_POSTFIX "d"