Add code to detect rst2html.py or rst2html

Makefile.am

@@ -1,13 +1,18 @@
 SUBDIRS =  po intl lib deps src doc test
 
 ACLOCAL_AMFLAGS = -I m4 --install
+RST2HTML = @RST2HTML@
 
 EXTRA_DIST = config.rpath mingw-config android-config android-make\
 	build_osx_release.sh
 
-dist_doc_DATA = README README.rst README.html
+dist_doc_DATA = README README.rst
+
+if HAVE_RST2HTML
+dist_doc_DATA += README.html
+README.html: README.rst
+	$(RST2HTML) README.rst > README.html
+endif # HAVE_RST2HTML
 
 dist_noinst_DATA = LICENSE.OpenSSL
 
-README.html: README.rst
-	rst2html README.rst > README.html

configure.ac

@@ -83,6 +83,10 @@ AC_PATH_PROG([ASCIIDOC], [asciidoc])
 AC_SUBST([ASCIIDOC])
 AM_CONDITIONAL([HAVE_ASCIIDOC], [ test "x$ASCIIDOC" != "x" ])
 
+AC_PATH_PROGS([RST2HTML], [rst2html.py rst2html])
+AC_SUBST([RST2HTML])
+AM_CONDITIONAL([HAVE_RST2HTML], [ test "x$RST2HTML" != "x" ])
+
 # Setting language choice
 AC_LANG([C++])