PE: don't corrupt section flags when linking from ELF objects

PE: don't corrupt section flags when linking from ELF objects

Linking EFI executables from ELF object files can result in corrupted
COFF section flags if the section's alignment is too high. Issue a
diagnostic in that case, erroring out if this is not a final link, and
make sure only in-range values get written to the output image.

While doing this also make tic80 use the generic alignment macros
instead of custom #ifdef-ary.

No testsuite regressions for the range of COFF/PE targets that actually
cross-build in the first place on x86-64-linux.