main/chrony: adjust path to sendmail(1)

The default configuration assumes that sendmail is located at
/usr/lib/sendmail, however, the sendmail version shipped by busybox is
located at /usr/sbin/sendmail.

main/chrony/APKBUILD

@@ -1,7 +1,7 @@
 # Maintainer: Natanael Copa <ncopa@alpinelinux.org>
 pkgname=chrony
 pkgver=2.1.1
-pkgrel=4
+pkgrel=5
 _ver=${pkgver/_/-}
 pkgdesc="NTP client and server programs"
 url="http://chrony.tuxfamily.org/"
@@ -51,6 +51,7 @@ build() {
 		--sysconfdir=/etc/$pkgname \
 		--disable-readline \
 		--with-user=$pkgname \
+		--with-sendmail=/usr/sbin/sendmail \
 		|| return 1
 
 	make all docs || return 1