Add configure check for python program

Add a configure check that looks for python3 and python in that order
since we had agreed in the past to prefer python3 over python in all
our code.  The patch also adjusts invocations through the various
Makefiles to use the set variable.

	* configure.ac: Check for python3 or python.
	* configure: Regenerated.
	* config.make.in (PYTHON): New variable.
	* benchtests/Makefile: Don't define PYTHON.
	(bench): Define target only if PYTHON was defined.
	* Rules: Don't define PYTHON.
	Define pretty printer targets only if PYTHON was defined.
	(tests-printers): Add to tests-unsupported if PYTHON is not
	found.
	(python-flags, python-invoke): Remove.
	(tests-printers-out): Use PYTHON instead of python-invoke.

1 files changed, 60 insertions, 2 deletions

diff --git a/configure b/configure
index 5cf3230b56..10b0fb7069 100755
--- a/configure
+++ b/configure
@@ -639,6 +639,8 @@ CXX_CMATH_HEADER
 CXX_CSTDLIB_HEADER
 CXX_SYSINCLUDES
 SYSINCLUDES
+PYTHON
+PYTHON_PROG
 AUTOCONF
 NM
 AWK
@@ -5086,17 +5088,73 @@ else
   AUTOCONF=no
 fi
 
+# Check for python3 if available, or else python.
+for ac_prog in python3 python
+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:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_PYTHON_PROG+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$PYTHON_PROG"; then
+  ac_cv_prog_PYTHON_PROG="$PYTHON_PROG" # Let the user override the test.
+else
+as_save_IFS=$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 '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_prog_PYTHON_PROG="$ac_prog"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+PYTHON_PROG=$ac_cv_prog_PYTHON_PROG
+if test -n "$PYTHON_PROG"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $PYTHON_PROG" >&5
+$as_echo "$PYTHON_PROG" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+  test -n "$PYTHON_PROG" && break
+done
+test -n "$PYTHON_PROG" || PYTHON_PROG="no"
+
+case "x$PYTHON_PROG" in
+xno|x|x:) PYTHON_PROG=no ;;
+*) ;;
+esac
+
+if test "x$PYTHON_PROG" = xno; then
+  aux_missing="$aux_missing python"
+else
+  PYTHON="$PYTHON_PROG -B"
+
+fi
+
 test -n "$critic_missing" && as_fn_error $? "
 *** These critical programs are missing or too old:$critic_missing
 *** Check the INSTALL file for required versions." "$LINENO" 5
 
 test -n "$aux_missing" && { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING:
 *** These auxiliary programs are missing or incompatible versions:$aux_missing
-*** some features will be disabled.
+*** some features or tests will be disabled.
 *** Check the INSTALL file for required versions." >&5
 $as_echo "$as_me: WARNING:
 *** These auxiliary programs are missing or incompatible versions:$aux_missing
-*** some features will be disabled.
+*** some features or tests will be disabled.
 *** Check the INSTALL file for required versions." >&2;}
 
 # if using special system headers, find out the compiler's sekrit