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/bacprop.h

@@ -26,6 +26,7 @@
 
 #include <stdbool.h>
 #include <stdint.h>
+#include "bacnet/bacnet_stack_exports.h"
 #include "bacnet/bacenum.h"
 
 typedef struct {
@@ -37,11 +38,13 @@ typedef struct {
 extern "C" {
 #endif /* __cplusplus */
 
+    BACNET_STACK_EXPORT
     signed bacprop_tag_by_index_default(
         PROP_TAG_DATA * data_list,
         signed index,
         signed default_ret);
 
+    BACNET_STACK_EXPORT
     signed bacprop_property_tag(
         BACNET_OBJECT_TYPE type,
         signed prop);