Use $< only in implicit rules. Non-gnu implementation of make expand

it to a null string if used within an explicit rule.

@@ -54,7 +54,7 @@ ETAGS_ARGS = --regex='/SCM_\(GLOBAL_\)?\(G?PROC\|G?PROC1\|SYMBOL\|VCELL\|CONST_L
 
 GUILE_DOC_SNARF=$(top_srcdir)/scripts/guile-$(GUILE_SNARF_VERSION)/guile-doc-snarf
 
-SUFFIXES=.x .doc .inc
+SUFFIXES=.x .doc .inc .in
 
 .c.x:
 	AWK=$(AWK) \
@@ -73,6 +73,8 @@ guile-procedures.txt: $(DOT_DOC_FILES)
 	cat $(DOT_DOC_FILES) > $@
 
 mailutils.scm: mailutils.scm.in $(libmu_scm_la_SOURCES:.c=.inc)
+
+.in:
 	m4 -DVERSION=$(VERSION) -DLIBDIR=$(libdir) \
            -DBUILDDIR=$(top_builddir)/libmu_scm $< > $@
 

@@ -92,7 +92,10 @@ mhlib_DATA = replcomps mhl.format $(LISPSRC)
 EXTRA_DIST = replcomps mhl.format mailutils-mh.eli mh_fmtgram.y pick.y
 DISTCLEANFILES = mailutils-mh.el
 
+SUFFIXES = .eli .el
 mailutils-mh.el: mailutils-mh.eli
+
+.eli.el:
 	sed "s,BINDIR,$(bindir),g;s,MHLIBDIR,$(mhlibdir),g" $< > $@
 
 INCLUDES = -I${top_srcdir}/include -I${top_srcdir}/lib -I${top_srcdir}/mailbox @INTLINCS@