Add libuserdefs and use in cmd/{oamuser,passwd}

@@ -221,10 +221,11 @@
         libtnfprobe     \
         libtsnet        \
         libtsol         \
         libumem         \
         libunistat      \
+        libuserdefs     \
         libuuid         \
         libuutil        \
         libvolmgt       \
         libvrrpadm      \
         libvscan        \