Revert "[fuzzer] Add attributes to LLVMFuzzerInitialize definition."

This reverts commit 004f348a.

Reason for revert: Breaks msvc compile: https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20msvc/builds/672

Original change's description:
> [fuzzer] Add attributes to LLVMFuzzerInitialize definition.
> 
> That prevents the linker from dead-stripping the function, as it is not called
> directly, it is resolved in the runtime via dlsym().
> 
> Bug: chromium:754124, chromium:787723
> Change-Id: I46a02ef01349f59b7ed944ce1483b7277e234a19
> Reviewed-on: https://chromium-review.googlesource.com/833995
> Commit-Queue: Max Moroz <mmoroz@chromium.org>
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Reviewed-by: Mathias Bynens <mathias@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#50212}

TBR=ahaas@chromium.org,mmoroz@chromium.org,mathias@chromium.org

Change-Id: Iba35b55ee4d11aca0dfb9cffde7a6a51e0c8e46c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:754124, chromium:787723
Reviewed-on: https://chromium-review.googlesource.com/834548Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50213}

test/fuzzer/fuzzer-support.cc

@@ -89,11 +89,7 @@ bool FuzzerSupport::PumpMessageLoop(
 
 }  // namespace v8_fuzzer
 
-// Explicitly specify some attributes to avoid issues with the linker dead-
-// stripping the following function on macOS, as it is not called directly
-// by fuzz target. LibFuzzer runtime uses dlsym() to resolve that function.
-extern "C" __attribute__((used)) __attribute__((visibility("default"))) int
-LLVMFuzzerInitialize(int* argc, char*** argv) {
+extern "C" int LLVMFuzzerInitialize(int* argc, char*** argv) {
   v8_fuzzer::FuzzerSupport::InitializeFuzzerSupport(argc, argv);
   return 0;
 }