package/elf2flt: replace hard-links with copies to fix rpath

Do for elf2flt what we did for binutils: replace the hardlinks (which
break rpath handling) with copies of the individaul tools.

See previous commit (package/binutils: switch from symlinks to copies
and commit f9cffb6a (binutils: replace hard-links with soft-links to
fix rpath) for the complete story.

Fixes: #11031.

Reported-by: Christophe Priouzeau <christophe.priouzeau@st.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Christophe Priouzeau <christophe.priouzeau@st.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Peter Korsgaard <peter@korsgaard.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>