don't fail dring make if a program to build documentation is not

found.

[[Imported from SVN: r965]]

configure.ac

@@ -14,6 +14,13 @@ AC_PROG_CXX
 AC_DISABLE_SHARED
 AC_PROG_LIBTOOL
 
+# check for auxiliary tools so that it's not fatal if they're missing
+AC_CHECK_PROGS([DOXYGEN], [doxygen], [true])
+AC_CHECK_PROGS([TEX], [latex], [true])
+AC_CHECK_PROGS([BIBTEX], [bibtex], [true])
+AC_CHECK_PROGS([DVIPDF], [dvipdf], [true])
+AC_CHECK_PROGS([DVIPS], [dvips], [true])
+
 # write output
 AC_CONFIG_FILES([Makefile
 	         common/Makefile

doc/Makefile.am

@@ -4,7 +4,7 @@ all: doxygen-tag
 
 doxygen-tag: Doxyfile
 @AMDEP_TRUE@	./Doxydep $< $(DEPDIR)/doxygen.Po $@
-	doxygen > doxygen.log 2>&1
+	$(DOXYGEN) > doxygen.log 2>&1
 	touch doxygen-tag
 
 WEBDIR = /var/www/dune/doxygen

istl/doc/Makefile.am

@@ -2,12 +2,6 @@
 
 dist_pkgdata_DATA = istl.pdf istl.ps
 
-# !! let autoconf find the binaries
-TEX = latex
-BIBTEX = bibtex
-DVIPDF = dvipdf
-DVIPS = dvips
-
 SUFFIXES = .dvi .tex .pdf
 
 # rerun TEX if log-file suggests that