Cleanup in the boilerplate that each target must define.
Replace arm_env_get_cpu with env_archcpu. The combination
CPU(arm_env_get_cpu) should have used ENV_GET_CPU to begin;
use env_cpu now.
Backports commit 2fc0cc0e1e034582f4718b1a2d57691474ccb6aa from qemu
Enforce that for M-profile various FPSCR bits which are RES0 there
but have defined meanings on A-profile are never settable. This
ensures that M-profile code can't enable the A-profile behaviour
(notably vector length/stride handling) by accident.
Backports commit 5bcf8ed9401e62c73158ba110864ee1375558bf7 from qemu
Move all of the fp helpers out of helper.c into a new file.
This is code movement only. Since helper.c has no copyright
header, take the one from cpu.h for the new file.
Backports commit 37356079fcdb34e13abbed8ea0c00ca880c31247 from qemu
