[libfuzzer] custom crossover interface function.

Differential Revision: http://reviews.llvm.org/D21089

llvm-svn: 272054
diff --git a/llvm/lib/Fuzzer/FuzzerExtFunctions.def b/llvm/lib/Fuzzer/FuzzerExtFunctions.def
index 0a90462..dccec18 100644
--- a/llvm/lib/Fuzzer/FuzzerExtFunctions.def
+++ b/llvm/lib/Fuzzer/FuzzerExtFunctions.def
@@ -19,5 +19,10 @@
 EXT_FUNC(LLVMFuzzerCustomMutator, size_t,
          (uint8_t * Data, size_t Size, size_t MaxSize, unsigned int Seed),
          false);
+EXT_FUNC(LLVMFuzzerCustomCrossOver, size_t,
+         (const uint8_t * Data1, size_t Size1,
+          const uint8_t * Data2, size_t Size2,
+          uint8_t * Out, size_t MaxOutSize, unsigned int Seed),
+         false);
 
 // TODO: Sanitizer functions