When all the codepaths using manually set .arch/.fpu code is
behind runtime detection, the elf attributes should be suppressed.

This allows tools to know that the final built binary doesn't
strictly require these extensions.
Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit dcae2e32)
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>