civetweb: fix static linking with openssl

Fixes http://autobuild.buildroot.net/results/acf/acfefc4f0f23ef646094ec427c9502eab7b86736/



Corrects a number of issues with the openssl handling:
 - Libraries have to be listed after the object files using them, so pass
   openssl linker statements in LIBS rather than COPT
 - Openssl support library is libcrypto, not libcrypt
 - Openssl need zlib

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>