The PE header size calculation failed to take the PE magic and coff
header size into account, which will lead to header truncation if we are
writing only 5 sections.
CentOS 8 ships python 3.6 so let's try and stay compatible with that
since the only feature we're using that requires python 3.9 is the
streamlined type annotations which are trivial to convert back to
the older stuff to stay compatible with python 3.6.
At least shim will choke on an empty relocation section when loading the
binary. Note that the binary is still considered relocatable (just with
no base relocations to apply) as we do not set the
IMAGE_FILE_RELOCS_STRIPPED DLL characteristic.
This adds back sd-boot builds by using meson compile targets directly.
We can do this now, because userspace binaries use the special
dependency that allows us to easily separate flags, so that we don't
pass anything to EFI builds that shouldn't be passed.
Additionally, we pass a bunch of flags to hopefully disable/override any
distro provided flags that should not be used for EFI binaries.
Fixes: #12275
