File trng-external-catch.patch of Package trng

Index: trng4-4.25/CMakeLists.txt
===================================================================
--- trng4-4.25.orig/CMakeLists.txt
+++ trng4-4.25/CMakeLists.txt
@@ -14,6 +14,7 @@ endif()
 
 option(TRNG_ENABLE_TESTS "Enable/Disable the compilation of the TRNG tests" ON)
 option(TRNG_ENABLE_EXAMPLES "Enable/Disable the compilation of the TRNG examples" ON)
+option(USE_EXTERNAL_CATCH "Use system installed Catch2" ON)
 
 if(CMAKE_CXX_COMPILER_ID MATCHES GNU)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wpedantic -Wmaybe-uninitialized")
@@ -42,7 +43,11 @@ configure_package_config_file("cmake/Con
 
 add_subdirectory(trng)
 if(TRNG_ENABLE_TESTS)
-  add_subdirectory(external/Catch2)
+  if(USE_EXTERNAL_CATCH)
+	  find_package(Catch2 2 REQUIRED)
+  else(USE_EXTERNAL_CATCH)
+    add_subdirectory(external/Catch2)
+  endif()
   add_subdirectory(tests)
 endif()
 if(TRNG_ENABLE_EXAMPLES)