[libFuzzer] make LLVMFuzzerTestOneInput (the fuzzer target function) return int instead of void. The actual return value is not *yet* used (and expected to be 0). This change is API breaking, so the fuzzers will need to be updated.

llvm-svn: 249214
diff --git a/llvm/tools/llvm-mc-fuzzer/llvm-mc-fuzzer.cpp b/llvm/tools/llvm-mc-fuzzer/llvm-mc-fuzzer.cpp
index 7710f80..3f80e45 100644
--- a/llvm/tools/llvm-mc-fuzzer/llvm-mc-fuzzer.cpp
+++ b/llvm/tools/llvm-mc-fuzzer/llvm-mc-fuzzer.cpp
@@ -62,7 +62,7 @@
                cl::desc("Options to pass to the fuzzer"), cl::ZeroOrMore,
                cl::PositionalEatsArgs);
 
-void DisassembleOneInput(const uint8_t *Data, size_t Size) {
+int DisassembleOneInput(const uint8_t *Data, size_t Size) {
   char AssemblyText[AssemblyTextBufSize];
 
   std::vector<uint8_t> DataCopy(Data, Data + Size);
@@ -85,6 +85,7 @@
       break;
   } while (Consumed != 0);
   LLVMDisasmDispose(Ctx);
+  return 0;
 }
 
 int main(int argc, char **argv) {