postgres check for dtrace

actually no, this, from configure.in:

#
# DTrace
#
PGAC_ARG_BOOL(enable, dtrace, no,
              [build with DTrace support],
[AC_DEFINE([ENABLE_DTRACE], 1, 
           [Define to 1 to enable DTrace support. (--enable-dtrace)])
AC_CHECK_PROGS(DTRACE, dtrace)
if test -z "$DTRACE"; then
  AC_MSG_ERROR([dtrace not found])
fi
AC_SUBST(DTRACEFLAGS)])
AC_SUBST(enable_dtrace)