Convert googletest and nanopb CMake builds to add_subdirectory (#1522)

* Add a download-only boringssl ExternalProject

Match boringssl version to grpc submodule version

Note: not yet in use

* Split grpc into separate download and build tasks

This allows other external targets to download into the gRPC source tree
before grpc is actually built.

* Convert grpc to an http download

* Build googletest with add_subdirectory

Also:
  * Revert library-name modifications in the abseil-cpp build
  * Move abseil-cpp add_subdirectory build into place

* Build nanopb with add_subdirectory

* Force nanopb first to work around ODR violations

This is a temporary work-around for b/111328563.

1 files changed, 6 insertions, 6 deletions

diff --git a/Firestore/third_party/abseil-cpp/CMakeLists.txt b/Firestore/third_party/abseil-cpp/CMakeLists.txt
index 4b939fa..7318cd3 100644
--- a/Firestore/third_party/abseil-cpp/CMakeLists.txt
+++ b/Firestore/third_party/abseil-cpp/CMakeLists.txt
@@ -76,14 +76,14 @@ endif()
 
 ## check targets
 if(BUILD_TESTING)
-  check_target(GTest::GTest)
-  check_target(GTest::Main)
-  check_target(GMock::GMock)
+  check_target(gtest)
+  check_target(gtest_main)
+  check_target(gmock)
 
   list(APPEND ABSL_TEST_COMMON_LIBRARIES
-    GTest::GTest
-    GTest::Main
-    GMock::GMock
+    gtest_main
+    gtest
+    gmock
     ${CMAKE_THREAD_LIBS_INIT}
   )
 endif()