x86: allow @secrel32 also in data definitions

x86: allow @secrel32 also in data definitions

Now that lex_got() is uniform for all targets using it, permit COFF
targets to also use @secrel32 with, in particular, .long. This is more
natural than the custom .secrel32 directive, and also allows more
flexibility (the "+six" form of the two added test lines doesn't work
with a .secrel32 equivalent, in that it silently produces an unintended
relocation type).

As an extra benefit this also makes sure that data definitions in Intel
syntax mode would get treated like they do for e.g. ELF targets.