Some trivial changes to compile under most recent MSVC as a CMake sub-project (#9275)

* Add a workaround for Filament's breaking change to add_subdirectory for Abseil, see: https://github.com/google/filament/issues/8611

* Fix #pragma warning syntax for MSVC

* Only search for an external Abseil dependency if a new option FILAMENT_USE_EXTERNAL_ABSL is set

filament/src/details/View.h

@@ -82,8 +82,8 @@ class JobSystem;
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
 #elif defined(_MSC_VER)
-#pragma warning push
-#pragma warning disable : 4996
+#pragma warning(push)
+#pragma warning(disable : 4996)
 #endif
 
 namespace filament {
@@ -663,7 +663,7 @@ FILAMENT_DOWNCAST(View)
 #if defined(__clang__)
 #pragma clang diagnostic pop
 #elif defined(_MSC_VER)
-#pragma warning pop
+#pragma warning(pop)
 #endif
 
 #endif // TNT_FILAMENT_DETAILS_VIEW_H

third_party/abseil/tnt/CMakeLists.txt

@@ -1,4 +1,10 @@
-add_subdirectory(../ "${CMAKE_CURRENT_BINARY_DIR}/abseil")
+option(FILAMENT_USE_EXTERNAL_ABSL "Use find_package to locate an external Abseil dependency" OFF)
+
+if (FILAMENT_USE_EXTERNAL_ABSL)
+  find_package(absl CONFIG QUIET)
+else()
+  add_subdirectory(../ "${CMAKE_CURRENT_BINARY_DIR}/abseil")
+endif()
 
 # To make Abseil easy for clients to link against, we create a dummy target just for installation
 # purposes and combine all of Abseil's libraries into a single, easy to link against static library.