libc/eglibc: fix installed scripts

Like rev 2002, eglibc installs some bash scripts, but use the path to the
buildtool bash as the interpreter (on the shebang line). This is only a
symlink to the real bash, and thus is not available at runtime.

Fix that by assuming that shell on the target *will* be /bin/bash.

Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>
(transplanted from 6884dcb80121ebc8ce17deee62716ed75fc29393)

 reporter_name="Thomas Petazzoni"

 reporter_url="http://www.free-electrons.com/"

 reporter_comment="Very basic testing only"