[gnumeric] configure: update python support.

[Morten Welinder <mortenw src gnome org>]

commit dfa17ac5d5ef5e2dc5da3ae8d2ee5227469ebb94
Author: Morten Welinder <terra gnome org>
Date:   Fri Oct 18 19:27:27 2019 -0400

    configure: update python support.
    
    1. Look for python3 before python2.
    2. Add a separate message at the end for python introspection
    
    Note: this effectively disables the python plugin.  Python introspection
    will continue to work.  Python2's is going away -- distributions are
    making noises about removal -- but you can still use --with-python to
    point at it.  Don't expect that to last.

 NEWS         |  1 +
 configure.ac | 43 +++++++++++++++++++++++++------------------
 2 files changed, 26 insertions(+), 18 deletions(-)
---
diff --git a/NEWS b/NEWS
index 6f29514f1..4716e9145 100644
--- a/NEWS
+++ b/NEWS
@@ -13,6 +13,7 @@ Morten:
        * Fix Mac build problem.  [#402]
        * Fix inter-process paste crash [#406]
        * Fix problem saving cell protection to xlsx.  [#409]
+       * Look for python3 before python.  [#419]
 
 --------------------------------------------------------------------------
 Gnumeric 1.12.45
diff --git a/configure.ac b/configure.ac
index 129ebcca3..94eaabffe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -417,7 +417,7 @@ AC_ARG_VAR(PSICONV_CONFIG, [The psiconv-config executable.])
 if test "x$with_psiconv" != xno; then
     AC_CHECK_PROG(PSICONV_CONFIG,psiconv-config,psiconv-config)
     if test x"$PSICONV_CONFIG" = x; then
-       psiconv_msg="missing dependencies"
+       psiconv_msg="Missing dependencies"
     else
        AC_MSG_CHECKING(for psiconv >= 0.9.3)
        if $PSICONV_CONFIG --version | awk -F. \
@@ -842,7 +842,7 @@ AM_CONDITIONAL(WITH_PERL, test "x$have_perl" = xyes)
 if test "x$have_perl" = xyes ; then
     perl_msg="yes (using $PERL)"
 else
-    perl_msg="no ($perl_reason)"
+    perl_msg="No. ($perl_reason)"
 fi
 AC_SUBST(PERL_CCCDLFLAGS)
 AC_SUBST(PERL_LDDLFLAGS)
@@ -868,7 +868,7 @@ If you want to specify a path to your Python executable, use:
        $srcdir/configure PYTHON=/path/to/your/python ...]);;
 esac
 if test "x$with_python" != xno; then
-    AC_PATH_PROGS(PYTHON, python python2 python2.7)
+    AC_PATH_PROGS(PYTHON, python3 python)
     if test "x$PYTHON" = x; then
        python_msg="could not find python"
     fi
@@ -880,6 +880,7 @@ fi
 # and the Python plugin
 have_python=no
 have_python_gi=no
+introspection_py_msg=no
 PYTHON_GIOVERRIDESDIR=
 if test "x$PYTHON" != x; then
     AC_DEFINE_UNQUOTED(PYTHON_INTERPRETER, ["$PYTHON"],
@@ -889,6 +890,7 @@ if test "x$PYTHON" != x; then
     AC_MSG_CHECKING([for python module gi])
     if $PYTHON -c 'import gi' 2>/dev/null; then
         have_python_gi=yes
+       introspection_py_msg="Yes."
        [PYTHON_GIOVERRIDESDIR=`$PYTHON -c 'import gi; import os.path; 
print(os.path.dirname(gi.__file__)+"/overrides")'`]
     fi
     AC_MSG_RESULT($have_python_gi)
@@ -897,6 +899,9 @@ AM_CONDITIONAL(HAVE_PYTHON_GI, test "x$have_python_gi" = "xyes")
 
 
 if test "x$python_msg" = xyes; then
+    # We're checking for python2 here, but we are likely to find python3.
+    # That's by design.
+    # Python2 is dead (or at least dying).
     BIG_CHECKING([for python = 2.x])
     [PY_VERSION=`$PYTHON -c 'import sys ; sys.stdout.write(sys.version[0:3])'`
      major_ver=`$PYTHON -c 'import sys ; sys.stdout.write(sys.version[0:1])'`]
@@ -907,8 +912,8 @@ if test "x$python_msg" = xyes; then
            PY_VERSION=`echo $PY_VERSION | sed -e 's/\\.//'`
        fi
     else
-       AC_MSG_RESULT(no)
-       python_msg="NO.  Python version \"${PY_VERSION}\" is too old."
+       AC_MSG_RESULT([no. $PYTHON is version $PY_VERSION])
+       python_msg="No.  This doesn't work with python3+ yet.  No ETA."
     fi
 fi
 
@@ -1042,6 +1047,7 @@ dnl presence/version checking
 AS_CASE([$enable_introspection],
 [no], [
     found_introspection="no (disabled, use --enable-introspection to enable)"
+    introspection_py_msg="No, introspection disabled"
 ],
 [yes],[
     PKG_CHECK_EXISTS([gobject-introspection-1.0],,
@@ -1280,21 +1286,22 @@ echo "
 
 Configuration:
 
-       Source code location:   ${srcdir}
-       Compiler:               ${CC}
-       Compiler flags:         ${CFLAGS}
-       Floating point type:    ${float_msg}
+       Source code location:           ${srcdir}
+       Compiler:                       ${CC}
+       Compiler flags:                 ${CFLAGS}
+       Floating point type:            ${float_msg}
 
-       UI:                     ${ui_msg}
+       UI:                             ${ui_msg}
 
-       Perl Support:           ${perl_msg}
-       Python Support:         ${python_msg}
+       Perl plugin support:            ${perl_msg}
+       Python plugin support:          ${python_msg}
+       Introspection python support:   ${introspection_py_msg}
 
-       GDA support:            ${gda_msg}
-       GNOME-DB support:       ${gnomedb_msg}
-       Psiconv support:        ${psiconv_msg}
+       GDA support:                    ${gda_msg}
+       GNOME-DB support:               ${gnomedb_msg}
+       Psiconv support:                ${psiconv_msg}
 
-       PDF documentation:      ${pdf_msg}
+       PDF documentation:              ${pdf_msg}
 "
-#      Mono support:           ${mono_msg}
-#      Guile Support:          ${guile_msg}
+#      Mono support:                   ${mono_msg}
+#      Guile Support:                  ${guile_msg}