Update Abseil version.

Define `RIEGELI_COMPARE()` for `absl::string_view` whenever
`!__cpp_impl_three_way_comparison`. `ABSL_USES_STD_STRING_VIEW` is now
always true so there is no need to consider it.

We assume that if `__cpp_impl_three_way_comparison` then `<=>` for standard
types is usable. Hopefully there is no need to consider implementations where
this does not apply.

PiperOrigin-RevId: 858951940

MODULE.bazel

diff --git a/MODULE.bazel b/MODULE.bazel
index 824fa80..ff1abe5 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -5,7 +5,7 @@
 
 bazel_dep(
     name = "abseil-cpp",
-    version = "20250814.0",
+    version = "20260107.0",
     repo_name = "com_google_absl",
 )
 bazel_dep(

riegeli/base/compare.h

diff --git a/riegeli/base/compare.h b/riegeli/base/compare.h
index 982f012..52eb456 100644
--- a/riegeli/base/compare.h
+++ b/riegeli/base/compare.h
@@ -206,11 +206,6 @@
                  : StrongOrdering::equal;
 }
 
-#endif
-
-#if !defined(__cpp_lib_three_way_comparison) || \
-    !defined(ABSL_USES_STD_STRING_VIEW)
-
 inline StrongOrdering RIEGELI_COMPARE(absl::string_view a,
                                       absl::string_view b) {
   return AsStrongOrdering(a.compare(b));