[libfuzzer] Roll libFuzzer 2ed967c..4d737af.

https://chromium.googlesource.com/chromium/llvm-project/llvm/lib/Fuzzer/+log/2ed967c..f2488e1

R=aizatsky@chromium.org, inferno@chromium.org, kcc@chromium.org, ochang@chromium.org
BUG=539572,674060

Review-Url: https://codereview.chromium.org/2570203003
Cr-Commit-Position: refs/heads/master@{#438804}

DEPS

@@ -100,7 +100,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling libFuzzer
   # and whatever else without interference from each other.
-  'libfuzzer_revision': '2ed967ccadb496a1e916d9bd33a41386900dfb6a',
+  'libfuzzer_revision': '4d737af21c2ce9e8b0655cd9397d83fa7956406c',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling devtools-node-modules
   # and whatever else without interference from each other.

third_party/libFuzzer/BUILD.gn

@@ -12,9 +12,13 @@ source_set("libfuzzer") {
     "src/FuzzerDriver.cpp",
     "src/FuzzerExtFunctionsDlsym.cpp",
     "src/FuzzerExtFunctionsWeak.cpp",
+    "src/FuzzerExtFunctionsWeakAlias.cpp",
     "src/FuzzerIO.cpp",
+    "src/FuzzerIOPosix.cpp",
+    "src/FuzzerIOWindows.cpp",
     "src/FuzzerLoop.cpp",
     "src/FuzzerMain.cpp",
+    "src/FuzzerMerge.cpp",
     "src/FuzzerMutate.cpp",
     "src/FuzzerSHA1.cpp",
     "src/FuzzerTracePC.cpp",
@@ -22,6 +26,8 @@ source_set("libfuzzer") {
     "src/FuzzerUtil.cpp",
     "src/FuzzerUtilDarwin.cpp",
     "src/FuzzerUtilLinux.cpp",
+    "src/FuzzerUtilPosix.cpp",
+    "src/FuzzerUtilWindows.cpp",
   ]
 }