[libFuzzer] Replace -seed_corpus to better support fork mode on Win

Summary:
Pass seed corpus list in a file to get around argument length limits on Windows.
This limit was preventing many uses of fork mode on Windows.

Reviewers: kcc, morehouse

Reviewed By: kcc

Subscribers: #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D60980

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@359610 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/FuzzerIO.h b/FuzzerIO.h
index cbfafa5..fe0d7b4 100644
--- a/FuzzerIO.h
+++ b/FuzzerIO.h
@@ -25,6 +25,8 @@
 void CopyFileToErr(const std::string &Path);
 
 void WriteToFile(const uint8_t *Data, size_t Size, const std::string &Path);
+// Write Data.c_str() to the file without terminating null character.
+void WriteToFile(const std::string &Data, const std::string &Path);
 void WriteToFile(const Unit &U, const std::string &Path);
 
 void ReadDirToVectorOfUnits(const char *Path, Vector<Unit> *V,