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/ImageMagick/template

@@ -6,7 +6,7 @@ version=${_distver}.${_distverpatch}
 revision=1
 wrksrc=${pkgname}-${_distver}-${_distverpatch}
 distfiles="http://ftp.nluug.nl/$pkgname/$pkgname-${_distver}-${_distverpatch}.tar.xz"
-build_style=gnu_configure
+build_style=gnu-configure
 configure_args="--without-gslib --without-jp2 --without-autotrace
 --without-djvu --without-dps --without-fpx --without-gvc --without-jbig
 --without-lqr --without-openexr --with-gs-font-dir=/usr/share/fonts/Type1