Revert "Export static symbols when building ws with shared library (#370)"

This reverts commit a3d2fa4b7e.

README.md

@@ -2,9 +2,7 @@
 
 IXWebSocket is a C++ library for WebSocket client and server development. It has minimal dependencies (no boost), is very simple to use and support everything you'll likely need for websocket dev (SSL, deflate compression, compiles on most platforms, etc...). HTTP client and server code is also available, but it hasn't received as much testing.
 
-It is been used on big mobile video game titles sending and receiving tons of messages since 2017 (iOS and Android). It was tested on macOS, iOS, Linux, Android, Windows and FreeBSD. Note that the MinGW compiler is not supported at this point. Two important design goals are simplicity and correctness.
-
-A bad security bug affecting users compiling with SSL enabled and OpenSSL as the backend was just fixed in newly released version 11.0.0. Please upgrade ! (more details in the [https://github.com/machinezone/IXWebSocket/pull/250](PR).
+It is been used on big mobile video game titles sending and receiving tons of messages since 2017 (iOS and Android). It was tested on macOS, iOS, Linux, Android, Windows and FreeBSD. Two important design goals are simplicity and correctness.
 
 ```cpp
 /*

ixwebsocket/IXSocketOpenSSL.cpp

@@ -339,12 +339,12 @@ namespace ix
         {
             int cn_pos = X509_NAME_get_index_by_NID(
                 X509_get_subject_name((X509*) server_cert), NID_commonName, -1);
-            if (cn_pos)
+            if (cn_pos >= 0)
             {
                 X509_NAME_ENTRY* cn_entry =
                     X509_NAME_get_entry(X509_get_subject_name((X509*) server_cert), cn_pos);
 
-                if (cn_entry)
+                if (cn_entry != nullptr)
                 {
                     ASN1_STRING* cn_asn1 = X509_NAME_ENTRY_get_data(cn_entry);
                     char* cn = (char*) ASN1_STRING_data(cn_asn1);