this reduces the size of the installed files by over half in most cases,
though the debug set size doesn't really change much (which looks like
close to 1GB of space on amd64 with xdebug installed, similar on arm64,
and about 600MB without xdebug.)
tested by running GDB on a few things, seems just as functional, on amd64,
arm64, and slightly on riscv64.
(first attempt for this feature used "gcc -gz=zlib", but that ends up
making CTF unhappy, but fortunately this works in binutils to create
the .debug files separate to any ctf usage of the main file.)
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