install location of math-vector-fortran.h

[Florian Weimer]

* Matthias Klose:

> this file currently only has lines like:
>
> !GCC$ builtin (cos) attributes simd (notinbranch) if('x86_64')
>
> so it shouldn't have any effect to other architectures?  Or are the
> conditionals explicitly done to exclude the 32bit x86 configuration?

Ah.  It's the latter.

Thanks,
Florian