[linux] set default data directory location to '/var/lib/boinc'.

Official BOINC packages for Linux use '/var/lib/boinc' directory instead of '/var/lib/boinc-client'.

This fixes #5775.

Signed-off-by: Vitalii Koshura <lestat.de.lionkur@gmail.com>

lib/common_defs.h

@@ -420,7 +420,7 @@ struct DEVICE_STATUS {
 // You can define this in "configure" if you want.
 //
 #ifndef LINUX_DEFAULT_DATA_DIR
-#define LINUX_DEFAULT_DATA_DIR      "/var/lib/boinc-client"
+#define LINUX_DEFAULT_DATA_DIR      "/var/lib/boinc"
 #endif
 
 #endif