main/dovecot: revert libexec move

/usr/lib/dovecot/dovecot is an incorrect location
/usr/libexec is allowed by FHS 3.0

main/dovecot/APKBUILD

@@ -5,7 +5,7 @@
 pkgname=dovecot
 pkgver=2.2.34
 _pkgvermajor=2.2
-pkgrel=2
+pkgrel=3
 _pigeonholever=0.4.21
 _pluginextdataver=39
 _pigeonholevermajor=${_pigeonholever%.*}
@@ -61,7 +61,6 @@ _configure() {
 build() {
 	cd "$builddir"
 	_configure \
-		--libexecdir=/usr/lib/$pkgname \
 		--with-gssapi=plugin \
 		--with-ldap=plugin \
 		--with-sql=plugin \