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

*** 442,451 ****
--- 442,452 ----
  file path=usr/lib/libsldap.so.1
  file path=usr/lib/libsmbios.so.1
  file path=usr/lib/libsoftcrypto.so.1
  file path=usr/lib/libsum.so.1
  file path=usr/lib/libsys.so.1
+ file path=usr/lib/libuserdefs.so.1
  $(sparc_ONLY)file path=usr/lib/libv12n.so.1
  file path=usr/lib/libvolmgt.so.1
  file path=usr/lib/libwrap.so.1.0
  file path=usr/lib/liby.so.1
  file path=usr/lib/libzoneinfo.so.1
*** 1185,1194 ****
--- 1186,1196 ----
  link path=usr/lib/libtsnet.so.1 target=../../lib/libtsnet.so.1
  link path=usr/lib/libtsol.so target=../../lib/libtsol.so.2
  link path=usr/lib/libtsol.so.2 target=../../lib/libtsol.so.2
  link path=usr/lib/libumem.so target=../../lib/libumem.so.1
  link path=usr/lib/libumem.so.1 target=../../lib/libumem.so.1
+ link path=usr/lib/libuserdefs.so target=./libuserdefs.so.1
  link path=usr/lib/libuuid.so target=../../lib/libuuid.so.1
  link path=usr/lib/libuuid.so.1 target=../../lib/libuuid.so.1
  link path=usr/lib/libuutil.so.1 target=../../lib/libuutil.so.1
  $(sparc_ONLY)link path=usr/lib/libv12n.so target=./libv12n.so.1
  link path=usr/lib/libvolmgt.so target=./libvolmgt.so.1