I was building this revision

https://github.com/libav/libav/tree/d6251368772a170987387bdc508433c8fcf54cda

on arm/termux it required --disable-asm but othervise worked. 

I applied 4 patches I fished out of mailbox archive with plain cat | patch - p1

patches attached. 

procedure seems to be documented in patches themselves:
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These changes add support for copying overlay streams.

So to extract IGS menu from m2ts file:
$ avconv -i source.m2ts -vn -an -sn output.mnu

To mux IGS menu with h264 video in ts:
$ avconv -i video.264 -i test.mnu -f mpegts out.ts
                                                                       
Still todo: update mpegts muxer to set correct PID so
output may be compatible to BDAV format.
                                                                       
Signed-off-by: David Girault <david at dhgirault.fr>
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