lvm2: install: fix "Argument list too long" error when copying symlinks

lvm2: install: fix "Argument list too long" error when copying symlinks

It was reported that in some build environments the install step fails
with following:

 find /home/.../buildsystem/build_dir/target-aarch64-unknown-linux-gnu_musl/lvm2-normal/LVM2.2.03.22/ipkg-install/usr/sbin/ -type l -exec cp -fpR -a {} /home/.../buildsystem/build_dir/target-aarch64-unknown-linux-gnu_musl/lvm2-normal/LVM2.2.03.22/.pkgdir/lvm2/sbin/ \;
 make[6]: /bin/sh: Argument list too long

This is likely happening once the number of symlinks exceeds the shell's
maximum argument limit.

So lets fix it by switching to more reliable xargs based solution:

 print0/xargs -0 to handle filenames with special characters
 xargs -r to skip execution if no files are found
 cp -t to specify the target directory once instead of for each file

Fixes: #26552
Signed-off-by: Petr Štetiar <[email protected]>