Mark Abseil container algorithms as constexpr for C++20.

This conditionally applies `constexpr` to the applicable container-based versions of the <algorithm> functions defined in "absl/algorithm/container.h" when building with C++20 or later.

PiperOrigin-RevId: 800165245
Change-Id: Ie2d0b16b2af84c3abd448ca15306e861d5e6c773

Author: avassalotti

absl/algorithm/BUILD.bazel

@@ -68,7 +68,7 @@ cc_library(
     deps = [
         ":algorithm",
         "//absl/base:config",
-        "//absl/base:nullability",
+        "//absl/base:core_headers",
         "//absl/meta:type_traits",
     ],
 )

absl/algorithm/CMakeLists.txt

@@ -49,8 +49,8 @@ absl_cc_library(
   DEPS
     absl::algorithm
     absl::config
+    absl::core_headers
     absl::meta
-    absl::nullability
   PUBLIC
 )
 
@@ -63,7 +63,6 @@ absl_cc_test(
     ${ABSL_TEST_COPTS}
   DEPS
     absl::algorithm_container
-    absl::base
     absl::config
     absl::core_headers
     absl::memory