Fix bazel build.

- https://reviews.llvm.org/D122619 bumped zlib version but didn't change
  the hash

- Added new header from https://reviews.llvm.org/D108438

Author: slackito

utils/bazel/WORKSPACE

@@ -37,7 +37,7 @@ maybe(
     http_archive,
     name = "zlib",
     build_file = "@llvm-raw//utils/bazel/third_party_build:zlib.BUILD",
-    sha256 = "c3e5e9fdd5004dcb542feda5ee4f0ff0744628baf8ed2dd5d66f8ca1197cb1a1",
+    sha256 = "91844808532e5ce316b3c010929493c0244f3d37593afd6de04f71821d5136d9",
     strip_prefix = "zlib-1.2.12",
     urls = [
         "https://storage.googleapis.com/mirror.tensorflow.org/zlib.net/zlib-1.2.12.tar.gz",

utils/bazel/llvm-project-overlay/llvm/BUILD.bazel

@@ -645,6 +645,7 @@ cc_library(
         "lib/Bitstream/Reader/*.h",
     ]),
     hdrs = [
+        "include/llvm/Bitstream/BitCodeEnums.h",
         "include/llvm/Bitstream/BitCodes.h",
         "include/llvm/Bitstream/BitstreamReader.h",
     ],
@@ -660,6 +661,7 @@ cc_library(
         "lib/Bitstream/Writer/*.h",
     ]),
     hdrs = [
+        "include/llvm/Bitstream/BitCodeEnums.h",
         "include/llvm/Bitstream/BitCodes.h",
         "include/llvm/Bitstream/BitstreamWriter.h",
     ],