bpo-45573: Introduce extension module flags in Makefile (GH-29594)

``configure`` now uses a standardized format to forward state, compiler
flags, and linker flags to ``Makefile``, ``setup.py``, and
``Modules/Setup``. ``makesetup`` use the new variables by default if a
module line does not contain any compiler or linker flags. ``setup.py``
has a new function ``addext()``.

For a module ``egg``, configure adds:

* ``MODULE_EGG`` with value yes, missing, disabled, or n/a
* ``MODULE_EGG_CFLAGS``
* ``MODULE_EGG_LDFLAGS``

``Makefile.pre.in`` may also provide ``MODULE_EGG_DEPS`` that lists
dependencies such as header files and static libs.

Signed-off-by: Christian Heimes <christian@python.org>

Modules/makesetup

@@ -154,6 +154,7 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
 		cpps=
 		libs=
 		mods=
+		mods_upper=
 		skip=
 		for arg in $line
 		do
@@ -194,11 +195,17 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
 			*.*)		echo 1>&2 "bad word $arg in $line"
 					exit 1;;
 			-u)		skip=libs; libs="$libs -u";;
-			[a-zA-Z_]*)	mods="$mods $arg";;
+			[a-zA-Z_]*)
+					mods="$mods $arg"
+					mods_upper=$(echo $mods | tr '[a-z]' '[A-Z]');;
 			*)		echo 1>&2 "bad word $arg in $line"
 					exit 1;;
 			esac
 		done
+		if test -z "$cpps" -a -z "$libs"; then
+			cpps="\$(MODULE_${mods_upper}_CFLAGS)"
+			libs="\$(MODULE_${mods_upper}_LDFLAGS)"
+		fi
 		case $doconfig in
 		yes)
 			LIBS="$LIBS $libs"
@@ -245,7 +252,6 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
 			*)
 				cc="$cc \$(PY_BUILTIN_MODULE_CFLAGS)";;
 			esac
-			mods_upper=$(echo $mods | tr '[a-z]' '[A-Z]')
 			# force rebuild when header file or module build flavor (static/shared) is changed
 			rule="$obj: $src \$(MODULE_${mods_upper}_DEPS) \$(PYTHON_HEADERS) Modules/config.c; $cc $cpps -c $src -o $obj"
 			echo "$rule" >>$rulesf