Apply clang format for samples files (#833)

Apply clang format for c source files under samples folder

samples/simple/src/main.c

@@ -3,8 +3,11 @@
  * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  */
 
-extern void iwasm_main();
-int main(int argc, char *argv[])
+extern void
+iwasm_main();
+
+int
+main(int argc, char *argv[])
 {
     iwasm_main(argc, argv);
     return 0;