[Build Reproducibility] Sort input file list (#35687)

Sort input file list
so that the `.so` file builds in a reproducible way
in spite of non-deterministic filesystem readdir order and
http://bugs.python.org/issue30461

See https://reproducible-builds.org/ for why this is good.

This patch was done while working on reproducible builds for openSUSE.




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Co-authored-by: Richard Belleville <rbellevi@google.com>

setup.py

@@ -361,7 +361,8 @@ if BUILD_WITH_SYSTEM_RE2:
     EXTENSION_LIBRARIES += ("re2",)
 if BUILD_WITH_SYSTEM_ABSL:
     EXTENSION_LIBRARIES += tuple(
-        lib.stem[3:] for lib in pathlib.Path("/usr").glob("lib*/libabsl_*.so")
+        lib.stem[3:]
+        for lib in sorted(pathlib.Path("/usr").glob("lib*/libabsl_*.so"))
     )
 
 DEFINE_MACROS = (("_WIN32_WINNT", 0x600),)