Export of internal Abseil changes

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6d4e969ad240d248bfeb644b3b76fffae0f07882 by Christian Blichmann <cblichmann@google.com>:

cmake: Fix description of `ABSL_USE_EXTERNAL_GOOGLETEST` option

There is no `add_subproject()` in CMake.

PiperOrigin-RevId: 443087953
Change-Id: I30c2118638f99ad1389ae197e2c81d1e5f298882
GitOrigin-RevId: 6d4e969ad240d248bfeb644b3b76fffae0f07882

CMakeLists.txt

@@ -111,7 +111,7 @@ option(ABSL_BUILD_TESTING
   "If ON, Abseil will build all of Abseil's own tests." OFF)
 
 option(ABSL_USE_EXTERNAL_GOOGLETEST
-  "If ON, Abseil will assume that the targets for GoogleTest are already provided by the including project. This makes sense when Abseil is used with add_subproject." OFF)
+  "If ON, Abseil will assume that the targets for GoogleTest are already provided by the including project. This makes sense when Abseil is used with add_subdirectory." OFF)
 
 cmake_dependent_option(ABSL_FIND_GOOGLETEST
   "If ON, Abseil will use find_package(GTest) rather than assuming that GoogleTest is already provided by the including project."