Fix doc generation

* doc/Makefile.am: Use tidy mode for texi2dvi; don't use
the deprecated texi2html.
* doc/tar.texi: Fix rendering of o-umlaut.
* doc/texify.sed: Likewise.

doc/Makefile.am

@@ -45,7 +45,7 @@ RENDITION = DISTRIB
 
 MAKEINFOFLAGS=-D$(RENDITION)
 
-header.texi: $(top_srcdir)/src/tar.h
+header.texi: $(top_srcdir)/src/tar.h texify.sed
 	sed -f $(srcdir)/texify.sed $(top_srcdir)/src/tar.h \
 	  | expand >$@
 
@@ -140,7 +140,7 @@ clean-local:
 
 GENDOCS=$(top_srcdir)/build-aux/gendocs.sh
 
-TEXI2DVI=texi2dvi -E
+TEXI2DVI=texi2dvi -E -I $(abs_srcdir) --build=tidy
 
 # Make sure you set TEXINPUTS
 # Usual value is:
@@ -149,6 +149,6 @@ manual:
 	TEXINPUTS=$(srcdir):$(top_srcdir)/build-tex:$(TEXINPUTS) \
 	 MAKEINFO="$(MAKEINFO) $(MAKEINFOFLAGS)" \
 	 TEXI2DVI="$(TEXI2DVI) -t '@set DISTRIB' -t @finalout" \
-	$(GENDOCS) --texi2html tar 'GNU tar manual'
+	$(GENDOCS) tar 'GNU tar manual'
 
 manual-rebuild: clean-local manual

doc/tar.texi

@@ -9730,7 +9730,7 @@ must be less than @math{2^21} (2,097,152).
 @end enumerate
 
 @item star
-The format used by the late J@"org Schilling's @command{star}
+The format used by the late J@"{o}rg Schilling's @command{star}
 implementation.  @GNUTAR{} can read @samp{star} archives but
 does not produce them.
 

doc/texify.sed

@@ -25,3 +25,4 @@ b
 s/\([{}]\)/@\1/g
 s,/\*,&@r{,
 s,\*/,}&,
+s/ö/@"{o}/g