Fix pragma once guard

From: Vlad Vissoultchev
    Date: Mon, 11 Apr 2016 01:26:32 +0300
    Subject: Fix pragma once guard when compiling multiple source files

    When compiling multiple source files directly to executable cached
    include files guard was incorrectly checked for TOK_once in ifndef_macro
    member.

    If two source files included the same header guarded by pragma once, then
    the second one erroneously skipped it as `cached_includes` is not cleared
    on second `tcc_compile`

tcc.c

@@ -344,7 +344,7 @@ int main(int argc, char **argv)
                         tcc_parse_args(s, argc - 1, argv + 1);
                         tcc_set_environment(s);
                         if (s->output_type != TCC_OUTPUT_OBJ)
-                            tcc_error("interlnal error");
+                            tcc_error("internal error");
                         tcc_set_output_type(s, s->output_type);
                     }
                 }