[libFuzzer] warn if the corpus is empty

llvm-svn: 266670
diff --git a/llvm/lib/Fuzzer/test/fuzzer.test b/llvm/lib/Fuzzer/test/fuzzer.test
index b42a49b..8794e88 100644
--- a/llvm/lib/Fuzzer/test/fuzzer.test
+++ b/llvm/lib/Fuzzer/test/fuzzer.test
@@ -118,3 +118,4 @@
 
 RUN: LLVMFuzzer-SimpleTest -runs=10 --max_len=100 2>&1 | FileCheck %s --check-prefix=DASH_DASH
 DASH_DASH: WARNING: did you mean '-max_len=100' (single dash)?
+DASH_DASH: INFO: A corpus is not provided, starting from an empty corpus