Refactor syscall to follow PintOS style in adding space after after function name in calls

src/userprog/syscall.c

@@ -20,14 +20,16 @@ static void exit (int status);
 static void *validate_user_pointer (void *ptr, size_t size);
 
 /* A struct defining a syscall_function pointer along with its arity. */
-typedef struct {
+typedef struct
+  {
     syscall_function function;    /* Function pointer. */
     int arity;                    /* Number of arguments of the function. */
   } syscall_arguments;
 
 /* A look-up table mapping numbers to system call functions with their number of
    arguments. */
-static const syscall_arguments syscall_lookup[] = {
+static const syscall_arguments syscall_lookup[] =
+{
   [SYS_HALT] = {(syscall_function) halt, 0},
   [SYS_EXIT] = {(syscall_function) exit, 1},
 };