build-sys: do not include id128-constants.h in the dist archive

File src/python-systemd/id128-constants.h is auto generated and its generation
does not require special tools, only sed.  There is no point in bundling it in
the distribution archive, so let's mark it as nodist_ to have it excluded.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=80006

Tested: Successfully ran "make dist" after ./configure --without-python.

Makefile.am

@@ -4774,10 +4774,12 @@ _journal_la_LIBADD = \
 
 id128_la_SOURCES = \
 	src/python-systemd/id128.c \
-	src/python-systemd/id128-constants.h \
 	src/python-systemd/pyutil.c \
 	src/python-systemd/pyutil.h
 
+nodist_id128_la_SOURCES = \
+	src/python-systemd/id128-constants.h
+
 id128_la_CFLAGS = \
 	$(AM_CFLAGS) \
 	-fvisibility=default \