[bazel] Update the mpfr URL to a stable one

mpfr has released a new version, and now the old tar.gz URL does not
work anymore. Update the URL to a stable one.

Author: gribozavr

utils/bazel/WORKSPACE

@@ -102,13 +102,16 @@ maybe(
 )
 
 # https://www.mpfr.org/mpfr-current/
+#
+# When updating to a newer version, don't use URLs with "mpfr-current" in them.
+# Instead, find a stable URL like the one used currently.
 maybe(
     http_archive,
     name = "mpfr",
     build_file = "@llvm-raw//utils/bazel/third_party_build:mpfr.BUILD",
     sha256 = "9cbed5d0af0d9ed5e9f8dd013e17838eb15e1db9a6ae0d371d55d35f93a782a7",
     strip_prefix = "mpfr-4.1.1",
-    urls = ["https://www.mpfr.org/mpfr-current/mpfr-4.1.1.tar.gz"],
+    urls = ["https://www.mpfr.org/mpfr-4.1.1/mpfr-4.1.1.tar.gz"],
 )
 
 maybe(