The ccid derivation provides a pcsclite plugin to access CCID devices.
This shared object is written to a non-standard path "$out/pcsc", which
causes it not to get stripped by default. The consequence is that the
result is an unstripped binary that still contains references to gcc and
glibc-dev in its debug symbols, which unnecessarily inflates the closure
size from ~80MB to ~400MB.
Explicitly add the directory to the stripped paths to fix this issue.
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