staging.bbclass: Don't stage doc/manpage/info files

There is no point in having doc, manpage or info files in the staging directory. They
just bloat the sstate package size and waste time as they're copied around.

We never used to stage these but it crept in when we started staging $datadir. This
patch corrects that so they're removed and stop making it into the sysroot.

(From OE-Core rev: ec4fea852bde2294ad7a7a703ccf11eb9a109c31)

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

meta/classes/staging.bbclass

@@ -51,6 +51,8 @@ sysroot_stage_dirs() {
 		sysroot_stage_libdir $from${base_libdir} $to${base_libdir}
 	fi
 	sysroot_stage_dir $from${datadir} $to${datadir}
+	# We don't care about docs/info/manpages
+	rm -rf $to${mandir}/ $to${docdir}/ $to${infodir}/
 }
 
 sysroot_stage_all() {