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/liba52/template

@@ -4,7 +4,7 @@ version=0.7.4
 revision=1
 wrksrc="a52dec-${version}"
 distfiles="http://liba52.sourceforge.net/files/a52dec-$version.tar.gz"
-build_style=gnu_configure
+build_style=gnu-configure
 configure_args="--enable-shared"
 short_desc="Free ATSC A/52 stream decoder"
 maintainer="Juan RP <xtraeme@gmail.com>"