BaseTools/GenFw: disable RVCT linker size optimization

Disable the RVCT size optimization that may put sections at an offset
that is not aligned to their own alignment, by adding the --no_legacyalign
switch to the RVCT linker command line. This is necessary since such sections
cannot be correctly converted into PE/COFF sections without padding them at
the front, which defeats the purpose of the optimization anyway.

With the optimization gone, we can also remove the special case for ARM in
GenFw that could result in corrupt PE/COFF images to be emitted. Instead,
sections whose base address is not aligned correctly are outright rejected.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18540 6f19259b-4bc3-4df7-8a09-765794883524