Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

Annotate arm userspace assembler sources stating their tolerance to
the non-executable stack.

Reviewed by: andrew
Sponsored by: The FreeBSD Foundation

Use a register to set the cpsr bits. The ip register is safe to be changed
within all of these functions, and is only stored in some to correctly pad
the stack.

This will be needed to build as Thumb-2 as, unlike with ARM instructions,
the msr instruction only takes a register as the input.

Add support for the __aeabi_c*cmp* functions. These are similar to the
existing functions with the exception they use the condition flags to
store the result.

Differential Revision: https://reviews.freebsd.org/D872
Silence from: current@ and numerics@
MFC after: 1 week