fix ugly configure output (follow up to #6943)

configure

 #! /bin/sh
-# From configure.in Revision: 78467 .
+# From configure.in Revision: 78817 .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.61 for python 2.7.
 #
@@ -15610,31 +15610,7 @@ echo "${ECHO_T}no" >&6; }
 fi
 
 
-# Check for use of the system expat library
-{ echo "$as_me:$LINENO: checking for --with-system-expat" >&5
-echo $ECHO_N "checking for --with-system-expat... $ECHO_C" >&6; }
-
-# Check whether --with-system_expat was given.
-if test "${with_system_expat+set}" = set; then
-  withval=$with_system_expat;
-fi
-
-
-{ echo "$as_me:$LINENO: result: $with_system_expat" >&5
-echo "${ECHO_T}$with_system_expat" >&6; }
-
-# Check for use of the system libffi library
-{ echo "$as_me:$LINENO: checking for --with-system-ffi" >&5
-echo $ECHO_N "checking for --with-system-ffi... $ECHO_C" >&6; }
-
-# Check whether --with-system_ffi was given.
-if test "${with_system_ffi+set}" = set; then
-  withval=$with_system_ffi;
-fi
-
-
-if test "$with_system_ffi" = "yes"; then
-    if test -n "$ac_tool_prefix"; then
+if test -n "$ac_tool_prefix"; then
   # Extract the first word of "${ac_tool_prefix}pkg-config", so it can be a program name with args.
 set dummy ${ac_tool_prefix}pkg-config; ac_word=$2
 { echo "$as_me:$LINENO: checking for $ac_word" >&5
@@ -15736,6 +15712,31 @@ else
   PKG_CONFIG="$ac_cv_path_PKG_CONFIG"
 fi
 
+
+# Check for use of the system expat library
+{ echo "$as_me:$LINENO: checking for --with-system-expat" >&5
+echo $ECHO_N "checking for --with-system-expat... $ECHO_C" >&6; }
+
+# Check whether --with-system_expat was given.
+if test "${with_system_expat+set}" = set; then
+  withval=$with_system_expat;
+fi
+
+
+{ echo "$as_me:$LINENO: result: $with_system_expat" >&5
+echo "${ECHO_T}$with_system_expat" >&6; }
+
+# Check for use of the system libffi library
+{ echo "$as_me:$LINENO: checking for --with-system-ffi" >&5
+echo $ECHO_N "checking for --with-system-ffi... $ECHO_C" >&6; }
+
+# Check whether --with-system_ffi was given.
+if test "${with_system_ffi+set}" = set; then
+  withval=$with_system_ffi;
+fi
+
+
+if test "$with_system_ffi" = "yes" && test -n "$PKG_CONFIG"; then
     LIBFFI_INCLUDEDIR="`"$PKG_CONFIG" libffi --cflags-only-I 2>/dev/null | sed -e 's/^-I//;s/ *$//'`"
 else
     LIBFFI_INCLUDEDIR=""

configure.in

@@ -2039,6 +2039,8 @@ LIBS="$withval $LIBS"
 ],
 [AC_MSG_RESULT(no)])
 
+AC_PATH_TOOL([PKG_CONFIG], [pkg-config])
+
 # Check for use of the system expat library
 AC_MSG_CHECKING(for --with-system-expat)
 AC_ARG_WITH(system_expat,
@@ -2051,8 +2053,7 @@ AC_MSG_CHECKING(for --with-system-ffi)
 AC_ARG_WITH(system_ffi,
             AC_HELP_STRING(--with-system-ffi, build _ctypes module using an installed ffi library))
 
-if test "$with_system_ffi" = "yes"; then
-    AC_PATH_TOOL([PKG_CONFIG], [pkg-config])
+if test "$with_system_ffi" = "yes" && test -n "$PKG_CONFIG"; then
     LIBFFI_INCLUDEDIR="`"$PKG_CONFIG" libffi --cflags-only-I 2>/dev/null | sed -e 's/^-I//;s/ *$//'`"
 else
     LIBFFI_INCLUDEDIR=""