Fix warning: "function declaration isn’t a prototype"

llvm-svn: 228139
diff --git a/llvm/include/llvm-c/lto.h b/llvm/include/llvm-c/lto.h
index 6df6e17..1fe0cd5 100644
--- a/llvm/include/llvm-c/lto.h
+++ b/llvm/include/llvm-c/lto.h
@@ -518,7 +518,7 @@
  * \since LTO_API_VERSION=12
  */
 extern unsigned int
-lto_api_version();
+lto_api_version(void);
 
 /**
  * Sets options to help debug codegen bugs.