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/ntp/template

@@ -4,7 +4,7 @@ version=4.2.6p4
 revision=3
 homepage="http://www.ntp.org/"
 distfiles="http://www.eecis.udel.edu/~ntp/ntp_spool/ntp4/ntp-$version.tar.gz"
-build_style=gnu_configure
+build_style=gnu-configure
 configure_args="--enable-linuxcap"
 short_desc="The Network Time Protocol"
 license="BSD"