Make maintainer-mode default to disabled

This makes the standard build instructions a bit easier,
just ./configure, and also requires less tools installed (bison).

Also i think few people probably want to generate the lexer and paser code.

.github/workflows/valgrind.yml

@@ -22,7 +22,6 @@ jobs:
         run: |
           autoreconf -i
           ./configure \
-            --disable-maintainer-mode \
             --disable-docs \
             --with-oniguruma=builtin
           make -j"$(nproc)"