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/bash/template

@@ -7,7 +7,7 @@ revision=1
 #version=${_bash_distver}
 wrksrc=${pkgname}-${_bash_distver}
 distfiles="http://ftp.gnu.org/gnu/bash/bash-${_bash_distver}.tar.gz"
-build_style=gnu_configure
+build_style=gnu-configure
 configure_args="--without-bash-malloc --with-curses --bindir=/bin
  --enable-array-variables --enable-brace-expansion --enable-casemod-attributes
  --enable-casemod-expansions --enable-command-timing --enable-cond-command