binutils: get rid of host-texinfo dependency and other documentation tricks

binutils: get rid of host-texinfo dependency and other documentation tricks

The binutils/host-binutils package applied several tricks to avoid building
info documentation. In the worst case, host-texinfo is added as dependency.

However, there is a simpler solution that removes the need for all these
tricks: instruct the makefiles to use a dummy makeinfo command ('true').

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>