wget: fix a host intrusion issue introduced by adding --with-ssl=openssl.

wget: fix a host intrusion issue introduced by adding --with-ssl=openssl.

On my x86-64 Ubuntu 11.04, with MACHINE=qemux86, "bitbake wget" fails. The
config.log shows:

configure:30072: i586-poky-linux-gcc  -m32   -march=i586
 --sysroot=/distro/dcui/1212/p1/build/tmp/sysroots/qemux86 -o conftest -O2
 -pipe -g -feliminate-unused-debug-types  -Wl,-O1 -Wl,--hash-style=gnu
 -Wl,--as-needed conftest.c -ldl -lz  /usr/lib/libssl.so /usr/lib/libcrypto.so
 -lz >&5
/usr/lib/libssl.so: could not read symbols: File in wrong format

The patch fixes the issue by specifying libssl-prefix.

Signed-off-by: Dexuan Cui <dexuan.cui@intel.com>