gcc on Microblaze is affected by PR63261, which causes a build failure
when optimization *and* debugging symbols are enabled. Since anyway
fxload is unlikely to be useful on Microblaze, let's disable this
package on this architecture.
Fixes:
http://autobuild.buildroot.net/results/24640a042d84f45339246c0a18e10905494b2199/
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>