void foo() is not a valid C prototype, one has to write void foo(void)

Remove a warning introduced in r262977

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 262990
diff --git a/llvm/tools/lto/lto.cpp b/llvm/tools/lto/lto.cpp
index 2c1417d..c6101a5 100644
--- a/llvm/tools/lto/lto.cpp
+++ b/llvm/tools/lto/lto.cpp
@@ -445,7 +445,7 @@
 
 // ThinLTO API below
 
-thinlto_code_gen_t thinlto_create_codegen() {
+thinlto_code_gen_t thinlto_create_codegen(void) {
   lto_initialize();
   ThinLTOCodeGenerator *CodeGen = new ThinLTOCodeGenerator();
   CodeGen->setTargetOptions(InitTargetOptionsFromCodeGenFlags());