c - zlib and gdi32 with OpenSSL? -

this follow question undefined reference rsa_generate_key in openssl? have openssl program generate rsa key, follows :

#include <stdio.h> #include <openssl/rsa.h> #include <openssl/pem.h>  int main(int argc, char* argv[])  {     rsa *r = null;     int ret;      r = rsa_new();     bignum *bne = null;     ret = rsa_generate_key_ex(r, 2048, bne, null);      return 0; } 

when compile

gcc -i../include rsatest.c -lcrypto -l. 

i undefined reference errors functions in libraries gdi32 , zlib.

so correct this, have add -lz , -lgdi32, as

gcc -i../include/ rsatest.c -lcrypto -lz -lgdi32 -l. 

my question is, aren't static libcrypto , libssl self sufficient? in why having add libraries make work? there option should have added while compiling library prevent this?

i'm using 64 bit windows mingw compiler. made openssl library of msys , make.