Export symbols in order to support shared libraries (#54)

* Add BAC_ROUTING compile definition

* Reorder cmake

* Fix OpenSSL support: support both 1.0 and 1.1t pus

* Explicitly export symbols, hidden by default

* Build shared libraries on travis using cmake

* Learn Makefile about static library

* Fix build using mingw with cmake

* Do not cleanup twice or after potential free

src/bacnet/basic/sys/debug.h

@@ -27,6 +27,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <stdio.h>
+#include "bacnet/bacnet_stack_exports.h"
 #include "bacnet/bacdef.h"
 
 #ifndef DEBUG_ENABLED
@@ -37,6 +38,7 @@
 extern "C" {
 #endif /* __cplusplus */
 
+    BACNET_STACK_EXPORT
     void debug_printf(
         const char *format,
         ...);