Clean up our ARM assembly:

MFC 275256:

Switch to the ARM unified assembly language as the clang integrated as only
supports it. Binutils supports it when the ".syntax unified" directive
is set.

Sponsored by: ABT Systems Ltd

MFC 275264:

Update _ENTRY to use _EENTRY to reduce the common code.

MFC 275321:

Remove extra labels, ENTRY_NP already provides them.

Sponsored by: ABT Systems Ltd

MFC 275322:

Correctly a few incorrect uses of ENTRY/EENTRY and END/EEND

Sponsored by: ABT Systems Ltd

MFC 275416:

Fix the name of the coprocessor to include the "p" prefix, the clang
integrated assembler expects this.

Sponsored by: ABT Systems Ltd

MFC 275418:

Switch to unified syntax so these can be built with clang 3.5.

Sponsored by: ABT Systems Ltd

MFC 275519:

Add missing END macros to some of the xscale functions.

Sponsored by: ABT Systems Ltd

MFC 275520:

Use the unified syntax in a few more assembly files

Sponsored by: ABT Systems Ltd

MFC 275521:

Set the alignment to 4-bytes after a string as clang 3.5 can switch to
thumb mode if this is incorrect.

Sponsored by: ABT Systems Ltd

MFC 275522:

Place the literal pool after a RET otherwise clang 3.5 tries to put it too
far away from a ldr psuedo instruction. With this clang will place the
literal value here where it's close enough to be loaded.

Sponsored by: ABT Systems Ltd

MFC 275523:

Switch to an armv6k cpu, without this clang 3.5 complains "bx lr" is
unsupported as it needs a newer cpu.

Sponsored by: ABT Systems Ltd

MFC 275524:

Switch to a .cpu directive. These will work when clang 3.5 is imported
where the .arch directive is a nop.

Sponsored by: ABT Systems Ltd

MFC r269390: Fix unwind info in hand-written asm (avoid nested functions).

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Fix ixp425 boot2 with ARM EABI:
- libkern is missing __aeabi_llsl, implement this by calling __ashldi3.
- Because of how the asm entry macros are defined the boot2 code
requires the unwind symbols to exist, include them in boot2.

Approved by: re (marius)

Add __aeabi_memset to libkern, implemented using memset, as clang may
generate calls to it.

Add END to ARM libkern assembly functions

Move the __aeabi_unwind_cpp_pr{0,1,2} functions to libkern so they can be
referenced in a non-debug kernel.

Add __aeabi_memcpy to libkern as clang may generate calls to it.

Add the required __aeabi_* functions the kernel uses when built for ARM EABI

Do not use __XSCALE__ to detect if clz is available, use _ARM_ARCH_5 instead.

MFC After: 3 days

/* -> /*- for copyright notices, minor format tweaks as necessary

Use the RET macro.

Implement ffs with clz for Xscale.
Idea taken from: NetBSD

Don't attempt to profile __udivsi3() and friends, as mcount() uses them.

Import libkern arm specific bits.