remove -Werror and use system wide GTest

Bug: https://bugs.gentoo.org/973597
Issue: https://github.com/facebook/yoga/issues/1934

diff --git a/cmake/project-defaults.cmake b/cmake/project-defaults.cmake
index 987529c5..6051621a 100644
--- a/cmake/project-defaults.cmake
+++ b/cmake/project-defaults.cmake
@@ -31,9 +31,8 @@ add_compile_options(
     -fno-omit-frame-pointer
     # Enable exception handling
     -fexceptions
-    # Enable warnings and warnings as errors
+    # Enable warnings
     -Wall
-    -Werror
     # Disable RTTI
     $<$<COMPILE_LANGUAGE:CXX>:-fno-rtti>
     # Use -O2 (prioritize speed)
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index c48bfb9f..fbf837f6 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -8,18 +8,13 @@ cmake_minimum_required(VERSION 3.13...3.26)
 project(tests)
 set(CMAKE_VERBOSE_MAKEFILE on)
 
-include(FetchContent)
 include(GoogleTest)
+find_package(GTest REQUIRED)
 
 set(YOGA_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/..)
 include(${YOGA_ROOT}/cmake/project-defaults.cmake)
 
 # Fetch GTest
-FetchContent_Declare(
-  googletest
-  URL https://github.com/google/googletest/archive/refs/tags/release-1.12.1.zip
-)
-FetchContent_MakeAvailable(googletest)
 
 add_subdirectory(${YOGA_ROOT}/yoga ${CMAKE_CURRENT_BINARY_DIR}/yoga)