Update build_style for all templates.

- There's no need to set build_style for custom-install (default).
- gnu_{configure,makefile} renamed to gnu-{configure,makefile}.

srcpkgs/readline/template

@@ -7,7 +7,7 @@ version=${_dist_ver}
 revision=1
 wrksrc=${pkgname}-${_dist_ver}
 distfiles="http://ftp.gnu.org/gnu/readline/${pkgname}-${_dist_ver}.tar.gz"
-build_style=gnu_configure
+build_style=gnu-configure
 configure_args="--with-curses --enable-multibyte"
 make_build_args="SHLIB_LIBS=-lncurses"
 short_desc="The GNU Readline Library"