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/glib-networking/template

@@ -2,7 +2,7 @@
 pkgname=glib-networking
 version=2.30.1
 distfiles="${GNOME_SITE}/$pkgname/2.30/$pkgname-$version.tar.xz"
-build_style=gnu_configure
+build_style=gnu-configure
 configure_args="--disable-static
 --with-ca-certificates=/etc/ssl/certs/ca-certificates.crt"
 short_desc="Network-related giomodules for glib"