Switch arm and arm64 over to the x86 style of jmpbuf.

Specifically, use the argument to sigsetjmp as a flag in the buffer
to indicate whether or not the signal mask is valid.

Bug: 16918359
Change-Id: I5bb1f1220f14c105c6bc57e0c28c1dc366d1438f
Merge "Switch arm and arm64 over to the x86 style of jmpbuf."
Use 64-bit units in the aarch64 setjmp implementation.

The use of 32-bit units for 64-bit stores and loads was driving me crazy.

Bug: 16918359
Change-Id: Ifb73aad8f8985a2adfcf5913b783ad9424f23e06
Merge "Use 64-bit units in the aarch64 setjmp implementation."
Switch arch-mips64/include/machine to a symlink.

Imagination already did the work to make the contents of these directories
identical. Let's take advantage of that fact.

Change-Id: Ib101ba39041fb500c9c618fa2020e72aa2ccd9c2
Merge "Switch arch-mips64/include/machine to a symlink."