vsftpd: add missing dependency on openssl

* Fails without openssl in sysroot:
  | i586-webos-linux-gcc  -m32 -march=i586 --sysroot=/OE/sysroots/qemux86 -o vsftpd main.o utility.o prelogin.o ftpcmdio.o postlogin.o privsock.o tunables.o ftpdataio.o secbuf.o ls.o postprivparent.o logging.o str.o netstr.o sysstr.o strlist.o banner.o filestr.o parseconf.o secutil.o ascii.o oneprocess.o twoprocess.o privops.o standalone.o hash.o tcpwrap.o ipaddrparse.o access.o features.o readwrite.o opts.o ssl.o sslslave.o ptracesandbox.o ftppolicy.o sysutil.o sysdeputil.o  -lssl -lcrypto -lnsl -lresolv -Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed -lcrypt -lcap
  | /OE/sysroots/x86_64-linux/usr/libexec/i586-webos-linux/gcc/i586-webos-linux/4.7.2/ld: cannot find -lssl
  | /OE/sysroots/x86_64-linux/usr/libexec/i586-webos-linux/gcc/i586-webos-linux/4.7.2/ld: cannot find -lcrypto
  | collect2: error: ld returned 1 exit status

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Joe MacDonald <joe.macdonald@windriver.com>