Remove zlib functions from the MSan blacklist

MOZ_Z_deflate: This doesn't exist anymore. Chromium uses Cr_z_
as prefix for zlib functions with external linkage.

longest_match: If there is an uninitialized use, we should fix
zlib instead of suppressing it. See the last bug below for a similar
issue. I'm hoping that if there is indeed an uninitialized use
in longest_match, and we have an existing test or fuzzer that hits it,
then we can extract a test case from that which also works upstream
(I wasn't able to repro based on what's in that referenced bug).

Bug: 116277,418383,1137613
Cq-Include-Trybots: luci.chromium.try:linux_chromium_msan_rel_ng
Change-Id: Ica7c0356cefcf6beb48d4a956cf9c839d310c880
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2510332
Commit-Queue: Hans Wennborg <hans@chromium.org>
Auto-Submit: Hans Wennborg <hans@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822755}

tools/msan/blacklist.txt

@@ -6,12 +6,6 @@
 # False positive in ffmpeg due to assembly code. http://crbug.com/344505
 fun:ff_get_cpu_flags_x86
 
-# Benign uninits in zlib.
-# http://crbug.com/116277
-fun:*MOZ_Z_deflate*
-# http://crbug.com/418383
-fun:longest_match
-
 # False positives due to use of linux_syscall_support. http://crbug.com/394028
 src:*/third_party/breakpad/breakpad/src/*
 src:*/components/crash/core/app/breakpad_linux.cc