vm_dump.c: adjust style

* vm_dump.c (backtrace): adjust style, inserting breaks between
  type, function name with its arguments, and its body.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46101 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

vm_dump.c

@@ -434,7 +434,9 @@ rb_vmdebug_thread_dump_state(VALUE self)
 #  define UNW_LOCAL_ONLY
 #  include <libunwind.h>
 #  undef backtrace
-int backtrace (void **trace, int size) {
+int
+backtrace(void **trace, int size)
+{
     unw_cursor_t cursor; unw_context_t uc;
     unw_word_t ip;
     int n = 0;