Unbundling abseil
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -97,7 +97,6 @@
   libgav1_dump_options()
 endif()
 
-set(libgav1_abseil_build "${libgav1_build}/abseil")
 set(libgav1_gtest_build "${libgav1_build}/gtest")
 
 # Compiler/linker flags must be lists, but come in from the environment as
@@ -109,8 +108,8 @@
   separate_arguments(LIBGAV1_EXE_LINKER_FLAGS)
 endif()
 
-add_subdirectory("${libgav1_root}/third_party/abseil-cpp"
-                 "${libgav1_abseil_build}" EXCLUDE_FROM_ALL)
+set(absl "/usr/lib/*/cmake/absl")
+find_package(absl REQUIRED)
 
 libgav1_reset_target_lists()
 libgav1_add_dsp_targets()