mark Windows binaries as compatible with ASLR

This is enough for dynamic libraries, but not executables because MinGW
does not output a .reloc section even with `--dynamicbase`. It could
either be worked around by exporting a DLL symbol from the executable or
fixed in MinGW itself.
auto merge of #16566 : thestinger/rust/aslr, r=pcwalton

This is enough for dynamic libraries, but not executables because MinGW
does not output a .reloc section even with `--dynamicbase`. It could
either be worked around by exporting a DLL symbol from the executable or
fixed in MinGW itself.