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/reccalc/scan.l

@@ -30,7 +30,7 @@
         while (capacity < size + yyleng + 1);           \
         str = realloc (str, capacity);                  \
       }                                                 \
-    strncpy (str + size, yytext, yyleng);               \
+    memcpy (str + size, yytext, yyleng);                \
     size += yyleng;                                     \
     assert (size < capacity);                           \
   } while (0)