lib: fix win32 compile error

[vs49688]

Fixes Win32 headers colliding with OpenSSL. X509_* specifically.

[  6%] Building C object rabbitmq-c/librabbitmq/CMakeFiles/rabbitmq-static.dir/amqp_openssl_hostname_validation.c.obj
In file included from /opt/x-tools/x86_64-w64-mingw32-cross/x86_64-w64-mingw32/include/windows.h:95,
                 from /opt/x-tools/x86_64-w64-mingw32-cross/x86_64-w64-mingw32/include/winsock2.h:23,
                 from /home/zane/Documents/Coding/nimrodg-agent/wb/x86_64-w64-mingw32/prefix/include/openssl/dtls1.h:64,
                 from /home/zane/Documents/Coding/nimrodg-agent/wb/x86_64-w64-mingw32/prefix/include/openssl/ssl.h:885,
                 from /home/zane/Documents/Coding/nimrodg-agent/rabbitmq-c/librabbitmq/amqp_openssl_hostname_validation.c:31:
/home/zane/Documents/Coding/nimrodg-agent/wb/x86_64-w64-mingw32/prefix/include/openssl/x509v3.h:194:2: error: expected specifier-qualifier-list before ‘(’ token
  194 |  X509_NAME *directoryName;
      |  ^~~~~~~~~
/home/zane/Documents/Coding/nimrodg-agent/wb/x86_64-w64-mingw32/prefix/include/openssl/x509v3.h:231:1: error: expected specifier-qualifier-list before ‘(’ token
  231 | X509_NAME *dpname;
      | ^~~~~~~~~
/home/zane/Documents/Coding/nimrodg-agent/wb/x86_64-w64-mingw32/prefix/include/openssl/x509v3.h:657:49: error: expected declaration specifiers or ‘...’ before ‘(’ token
  657 | int DIST_POINT_set_dpname(DIST_POINT_NAME *dpn, X509_NAME *iname);
      |                                                 ^~~~~~~~~
/home/zane/Documents/Coding/nimrodg-agent/wb/x86_64-w64-mingw32/prefix/include/openssl/x509v3.h:837:30: error: expected declaration specifiers or ‘...’ before ‘(’ token
  837 | int X509V3_NAME_from_section(X509_NAME *nm, STACK_OF(CONF_VALUE)*dn_sk,
      |                              ^~~~~~~~~

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This change is 

[alanxz]

Merged.

Thanks for the contribution!