It seems, ftp/pure-ftpd suffers from the same problem, www/apache22 had (see https://lists.freebsd.org/pipermail/freebsd-apache/2014-April/003483.html). Building with WITH_OPENSSL_PORT=yes works as expected on FreeBSD 9.x:

/usr/local/sbin/pure-ftpd:
	libmysqlclient.so.18 => /usr/local/lib/mysql/libmysqlclient.so.18 (0x801240000)
	libz.so.6 => /lib/libz.so.6 (0x80177f000)
	libm.so.5 => /lib/libm.so.5 (0x801993000)
	libssl.so.8 => /usr/local/lib/libssl.so.8 (0x801bb4000)
	libcrypto.so.8 => /usr/local/lib/libcrypto.so.8 (0x801e26000)
	libsodium.so.13 => /usr/local/lib/libsodium.so.13 (0x80224e000)
	libcrypt.so.5 => /lib/libcrypt.so.5 (0x8024af000)
	libthr.so.3 => /lib/libthr.so.3 (0x8026ce000)
	libc.so.7 => /lib/libc.so.7 (0x80081a000)
	libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x8028f0000)
	libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x802c00000)

but it uses the libraries from base when built on 10:

/usr/local/sbin/pure-ftpd:
	libmysqlclient.so.18 => /usr/local/lib/mysql/libmysqlclient.so.18 (0x801644000)
	libm.so.5 => /lib/libm.so.5 (0x801c23000)
	libssl.so.7 => /usr/lib/libssl.so.7 (0x801e4b000)
	libcrypto.so.7 => /lib/libcrypto.so.7 (0x8020b6000)
	libz.so.6 => /lib/libz.so.6 (0x8024aa000)
	libsodium.so.13 => /usr/local/lib/libsodium.so.13 (0x8026c0000)
	libcrypt.so.5 => /lib/libcrypt.so.5 (0x80291c000)
	libpam.so.5 => /usr/lib/libpam.so.5 (0x802b3c000)
	libthr.so.3 => /lib/libthr.so.3 (0x802d48000)
	libc.so.7 => /lib/libc.so.7 (0x80081f000)
	libc++.so.1 => /usr/lib/libc++.so.1 (0x802f6d000)
	libcxxrt.so.1 => /lib/libcxxrt.so.1 (0x80322d000)
	libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x803449000)