Don't attempt to build a local copy of GoogleTest.

--- third_party/CMakeLists.txt.orig	2025-02-03 23:57:26 UTC
+++ third_party/CMakeLists.txt
@@ -1,15 +1,5 @@ if(BUILD_FUZZTEST)
 if(BUILD_FUZZTEST)
   add_subdirectory(fuzztest)
-elseif(BUILD_TESTS)
-  # fuzztest includes gtest, but if we're not building fuzztest, build gtest ourselves.
-  add_library(gtest STATIC googletest/googletest/src/gtest-all.cc)
-  add_library(gtest_main STATIC googletest/googletest/src/gtest_main.cc)
-  target_compile_options(gtest PRIVATE "-fno-rtti")
-  target_compile_options(gtest_main PRIVATE "-fno-rtti")
-  include_directories(
-    googletest/googletest
-    googletest/googletest/include
-  )
 endif()
 
 if(BUILD_LLVM_DWARF)