Install library with correct executable permissions

Also use "install -p" to keep timestamps.
3 jobs for patch-1 in 4 minutes and 26 seconds
latest
Status Job ID Name Coverage
  Build
passed #289474
librem5
build-debian-gcc-buster

00:00:59

 
  Package
passed #289475
librem5
package:deb-debian-buster

00:01:14

passed #289476
librem5:arm64
package:deb-debian-buster:arm64

00:03:25