feat: support building using busybox (alpine linux)

[jbergstroem]

In systems that rely on busybox install -C is not available. This commit switches it for cp with the potential downside of not setting (changing) permissions. I doubt it will have an impact.

[dpxcc]

We use install -C instead of cp because it only copies the file if the content has changed
This is especially useful for incremental debug builds, as the libraries are quite large: libdelta.a (1.1G) and libduckdb.so (711M)

[dpxcc]

How about 569ff9a?
It uses install -C for debug builds, but install for release builds
Or we can make it depend on whether the system supports install -C or not

INSTALL_FLAGS := $(shell if install -C /dev/null /dev/null 2>/dev/null; then echo "-C"; else echo ""; fi)

[jbergstroem]

Makes sense, let me merge that in and give it a go.

[dpxcc]

This PR is out-dated after the v0.2 re-architecture