postgres check for dtrace

# Check whether --enable-dtrace was given.
if test "${enable_dtrace+set}" = set; then
  enableval=$enable_dtrace;
  case $enableval in
    yes)

cat >>confdefs.h <<\_ACEOF
#define ENABLE_DTRACE 1
_ACEOF

for ac_prog in dtrace
do
  # Extract the first word of "$ac_prog", so it can be a program name with args.
set dummy $ac_prog; ac_word=$2
{ $as_echo "$as_me:$LINENO: checking for $ac_word" >&5
$as_echo_n "checking for $ac_word... " >&6; }
if test "${ac_cv_prog_DTRACE+set}" = set; then
  $as_echo_n "(cached) " >&6
else
  if test -n "$DTRACE"; then
  ac_cv_prog_DTRACE="$DTRACE" # Let the user override the test.
else
as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
for as_dir in $PATH
do
  IFS=$as_save_IFS
  test -z "$as_dir" && as_dir=.
  for ac_exec_ext in '' $ac_executable_extensions; do
  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
    ac_cv_prog_DTRACE="$ac_prog"
    $as_echo "$as_me:$LINENO: found $as_dir/$ac_word$ac_exec_ext" >&5
    break 2
  fi
done
done
IFS=$as_save_IFS