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/mysql/template

@@ -2,7 +2,7 @@
 pkgname=mysql
 version=5.1.54
 distfiles="http://downloads.mysql.com/archives/mysql-5.1/$pkgname-$version.tar.gz"
-build_style=gnu_configure
+build_style=gnu-configure
 configure_args="--sysconfdir=/etc/mysql
 --with-libwrap --with-charset=utf8 --with-collation=utf8_general_ci
 --with-extra-charsets=complex --with-embedded-server --enable-local-infile