(glibc-io.struct): New target. Rework the code

that generates jm-glibc-io.m4 so that it doesn't trigger any make
distcheck failure.

m4/Makefile.am.in

@@ -6,13 +6,15 @@
 Makefile.am: Makefile.am.in
 	rm -f $@ $@t
 	sed -n '1,/^##m4-files-begin/p' $< > $@t
-	((echo EXTRA_DIST = README jm-glibc-io.m4n Makefile.am.in|tr '\012' @);\
+	(((echo EXTRA_DIST =; \
+	   echo "  README jm-glibc-io.m4 jm-glibc-io.m4n Makefile.am.in" \
+	  ) | tr '\012' @); \
 	  (echo *.m4|tr ' ' @) ) \
 	  |sed 's/@$$/%/;s/@/ \\@/g' |tr @% '\012\012' \
 	  >> $@t
 	sed -n '/^##m4-files-end/,$$p' $< >> $@t
 	echo >> $@t
-	echo all-local: jm-glibc-io.m4 >> $@t
+	echo all-local: glibc-io.stamp >> $@t
 	chmod a-w $@t
 	mv $@t $@
 
@@ -24,14 +26,27 @@ unlocked_functions = \
 
 comma_separated = $(shell echo $(unlocked_functions)|tr -s ' ' ,)
 base_functions = $(patsubst %_unlocked,%,$(unlocked_functions))
-jm-glibc-io.m4: jm-glibc-io.m4n Makefile
-	echo 'dnl This file is automatically generated from $<' > $@t
-	echo '' >> $@t
-	sed							\
-	  -e 's/@space_separated@/$(unlocked_functions)/g'	\
-	  -e 's/@comma_separated@/$(comma_separated)/g'		\
-	  $< >> $@t
-	move-if-change $@t $@
+
+# Don't depend directly on jm-glibc-io.m4, because that would cause it
+# to be created in non-srcdir==. builds, and that leads to problems with
+# distcheck.  Note also that we can't add it to DISTCLEANFILES for similar
+# reasons.
+glibc-io.stamp: jm-glibc-io.m4n Makefile
+	if test `pwd` = `cd $(srcdir); pwd`; then			\
+	  t=jm-glibc-io.m4;						\
+	  src=$(srcdir)/jm-glibc-io.m4n;				\
+	  echo "dnl This file is automatically generated from $${t}n."	\
+	    > $${t}t;							\
+	  echo '' >> $${t}t;						\
+	  sed								\
+	    -e 's/@space_separated@/$(unlocked_functions)/g'		\
+	    -e 's/@comma_separated@/$(comma_separated)/g'		\
+	    $$src >> $${t}t;						\
+	  move-if-change $${t}t $$t;					\
+	fi
+	touch $@
+
+DISTCLEANFILES = glibc-io.stamp
 
 unlocked-io.h: unlocked-io.hin Makefile.am.in
 	tmp=t$$$$;							\