package: various fixes for syntax-check

* cfg.mk: Disable checks where needed (e.g., we do want to check the
behavior with tabs).
(sc_at_parser_check): Remove.  Unfortunately since
a11c144609 we no longer use the './'
prefix to run programs in the current directory.  That was so that we
could run Java programs like the other, although they are no run with
the `./` prefix (see 967a59d2c0).
As a consequence this sc check no longer makes sense.
However, since now AT_PARSER_CHECK passes the `./` prefix itself, this
sc-check was superfluous.
* examples/c/reccalc/scan.l: Use memcpy, not strncpy.
* src/ielr.c, src/reader.c: Obfuscate "lr(0)" so that the sc-check for
"space before paren" does not fire.
* tests/diagnostics.at: Avoid space-tab, use tab-tab.

examples/c/calc/calc.y

@@ -87,7 +87,7 @@ main (int argc, char const* argv[])
 {
   /* Enable parse traces on option -p.  */
   for (int i = 1; i < argc; ++i)
-    if (!strcmp(argv[i], "-p"))
+    if (!strcmp (argv[i], "-p"))
       yydebug = 1;
   return yyparse ();
 }