Fixed issue with HAVE_DOXYGEN define

configure.ac

@@ -435,6 +435,10 @@ char	string[16];
 ]
 )
 
+AC_PATH_PROG([DOXYGEN], [doxygen], [])
+AM_CONDITIONAL([HAVE_DOXYGEN], [test -n "$DOXYGEN"])
+AM_COND_IF([HAVE_DOXYGEN], AC_CONFIG_FILES([doc/Doxyfile]))
+
 #AC_CONFIG_FILES([Makefile])
 AC_OUTPUT(Makefile bin/Makefile man/Makefile)
 

doc/Makefile.am

@@ -1,15 +1,24 @@
-#if HAVE_DOXYGEN
-
 directory = $(top_srcdir)/doc
 
-$(directory)/html: Doxyfile
+if HAVE_DOXYGEN
+
+doxygen-build.stamp: Doxyfile
 	$(DOXYGEN) Doxyfile
+	touch $@
+
+else
+
+doxygen-build.stamp:
+	@echo "*** Doxygen not found. Documentation will not be build."
+	touch $@
+
+endif
 
-all-local: $(directory)/html
+all-local: doxygen-build.stamp
 
 clean-local:
-	rm -rf $(directory)/html
-	rm -rf $(directory)/man
-	rm -rf $(directory)/xml
+	rm -f doxygen-build.stamp
+	rm -rf html
+	rm -rf man
+	rm -rf xml
 
-#endif