msvc: copy the correct `.pdb` files in the Makefile target `install`

msvc: copy the correct `.pdb` files in the Makefile target `install`

There is a hard-coded list of `.pdb` files to copy. But we are about to
introduce the `SKIP_DASHED_BUILT_INS` knob in the `Makefile`, which
might make this hard-coded list incorrect.

Let's switch to a dynamically-generated list instead.

Signed-off-by: Johannes Schindelin <redacted>
Signed-off-by: Junio C Hamano <redacted>