Since 0.60.0, upstream renamed to "ocsync".

--- cmake/Modules/FindCSYNC.cmake
+++ cmake/Modules/FindCSYNC.cmake
@@ -20,7 +20,7 @@
 else (CSYNC_LIBRARIES AND CSYNC_INCLUDE_DIRS)
   find_path(CSYNC_INCLUDE_DIR
     NAMES
-      csync/csync.h
+      ocsync/csync.h
     PATHS
       /usr/include
       /usr/local/include
@@ -30,7 +30,7 @@
 
   find_library(CSYNC_LIBRARY
     NAMES
-      csync
+      ocsync
     PATHS
       /usr/lib
       /usr/local/lib
--- src/pam_csync.c
+++ src/pam_csync.c
@@ -50,7 +50,7 @@
 #include <security/pam_modutil.h>
 #include <security/pam_ext.h>
 
-#include <csync/csync.h>
+#include <ocsync/csync.h>
 
 #include "pam_csync.h"
 #include "config.h"