Fix build-many-glibcs.py arm-linux-gnueabihf builds with mainline GCC.

My fix to make the arm-linux-gnueabihf build-many-glibcs.py builds
actually use the hard-float ABI as intended showed up another issue
when building with mainline GCC: GCC now determines an FPU based on
the selected CPU or architecture and gives an error for
-mfloat-abi=hard when the CPU does not imply a choice of FPU.  This
patch fixes all the affected configurations to specify a suitable
--with-cpu, --with-fpu or -mfpu option explicitly to avoid that error
from GCC.

Tested the relevant configurations with build-many-glibcs.py with
mainline GCC.

	* scripts/build-many-glibcs.py (Context.add_all_configs): Specify
	CPU or FPU for ARM hard-float configurations.