SSH: fix compilation issues that arose with GCC 4.7. This fixes #4684.

ssh/build/CMakeLists.txt

@@ -233,6 +233,7 @@ target_link_libraries(
   ${LIBSSH2_LIBRARIES}
   ${CLIB_LIBRARIES}
   ${LIBGCRYPT_LIBRARIES}
+  "pthread"
 )
 
 # SSH connector.

ssh/src/sessions/session.cc

@@ -29,6 +29,7 @@
 #include <netinet/in.h>
 #include <pwd.h>
 #include <sys/socket.h>
+#include <unistd.h>
 #include "com/centreon/connector/ssh/multiplexer.hh"
 #include "com/centreon/connector/ssh/sessions/session.hh"
 #include "com/centreon/exceptions/basic.hh"