poco: fix sh4a fenv build failure
Disable FP environment on sh4a. Fixes
http://autobuild.buildroot.net/results/8dc9bca5969d455cc30206fc1ae6e1d3ba6eb6ca/.
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>