cmake: support gtest from the package manager (#552)

Some developers would be happier with the gtest version provided from
their package manager. Use it if it is installed the package provide
cmake support.

Fixed: https://github.com/ArthurSonzogni/FTXUI/issues/551

cmake/ftxui_benchmark.cmake

@@ -1,31 +1,21 @@
-if (NOT WIN32)
-  FetchContent_Declare(googlebenchmark
-    GIT_REPOSITORY "https://github.com/google/benchmark"
-    GIT_TAG 62937f91b5c763a8e119d0c20c67b87bde8eff1c 
-    GIT_PROGRESS TRUE
-  )
-
-  FetchContent_GetProperties(googlebenchmark)
-  set (BENCHMARK_ENABLE_GTEST_TESTS OFF CACHE INTERNAL "")
-  set (BENCHMARK_ENABLE_TESTING OFF CACHE INTERNAL "")
-  if(NOT googlebenchmark_POPULATED)
-    FetchContent_Populate(googlebenchmark)
-    add_subdirectory(
-      ${googlebenchmark_SOURCE_DIR}
-      ${googlebenchmark_BINARY_DIR}
-      EXCLUDE_FROM_ALL
+if (NOT FTXUI_BUILD_TESTS OR
+    NOT ${CMAKE_VERSION} VERSION_GREATER "3.11.4" OR
+    WIN32
     )
-  endif()
-
-  add_executable(ftxui_benchmark
-    src/ftxui/dom/benchmark_test.cpp
-  )
-  target_link_libraries(ftxui_benchmark
-    PRIVATE dom
-    PRIVATE benchmark::benchmark
-    PRIVATE benchmark::benchmark_main
-  )
-  target_include_directories(ftxui_benchmark
-    PRIVATE src
-  )
+  return()
 endif()
+
+include(cmake/ftxui_find_google_benchmark.cmake)
+
+add_executable(ftxui-benchmark
+  src/ftxui/dom/benchmark_test.cpp
+  )
+ftxui_set_options(ftxui-benchmark)
+target_link_libraries(ftxui-benchmark
+  PRIVATE dom
+  PRIVATE benchmark::benchmark
+  PRIVATE benchmark::benchmark_main
+  )
+target_include_directories(ftxui-benchmark
+  PRIVATE src
+  )