Do not use bool in C header lto.h, use lto_bool_t instead

llvm-svn: 275130
diff --git a/llvm/include/llvm-c/lto.h b/llvm/include/llvm-c/lto.h
index 655aedc..b1f5a45d 100644
--- a/llvm/include/llvm-c/lto.h
+++ b/llvm/include/llvm-c/lto.h
@@ -141,7 +141,8 @@
  *
  * \since LTO_API_VERSION=20
  */
-bool lto_module_has_objc_category(const void *mem, size_t length);
+extern lto_bool_t
+lto_module_has_objc_category(const void *mem, size_t length);
 
 /**
 * Checks if a buffer is a loadable object file.