autoconf: Add fix for sh verses bash issues

Libtool scripts were finding bash was /bin/sh and then using bashisms which
then got into sstate and used on machines where /bin/sh might be dash.

This changes things to search for bash first since its preferred. We then hardcode
bash into the scripts which is more correct.

This does mean we have a dependency on bash but many of our scripts have
that anyway.

(From OE-Core rev: 367a19aaf31bcf997f10d045e7954cc800189052)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/autoconf/autoconf_2.69.bb

@@ -16,6 +16,7 @@ SRC_URI += "file://autoreconf-include.patch \
 	    ${@['file://path_prog_fixes.patch', ''][bb.data.inherits_class('native', d) or bb.data.inherits_class('nativesdk', d)]} \
             file://config_site.patch \
             file://remove-usr-local-lib-from-m4.patch \
+            file://preferbash.patch \
            "
 
 SRC_URI[md5sum] = "82d05e03b93e45f5a39b828dc9c6c29b"