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

cmake/Config.cmake.in

@@ -1,4 +1,8 @@
 @PACKAGE_INIT@
 
+if("@CMAKE_SYSTEM_NAME@" STREQUAL "Linux" OR APPLE OR WIN32)
+    find_package(OpenSSL REQUIRED)
+endif()
+
 include("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")
 check_required_components("@PROJECT_NAME@")