Use atsign-simd for sum
Add arm specific configuration to help in the port.
Makefile changes to build on ARM
Add fake cpuid for ARM

TODO: proper implementation using procinfo
arm: use LLVM3.5
Rename Make.inc.arm to ARM.inc
Add checksums for llvm 3.5.0
Add basic ARM README
ARM.inc should have lower precedence than Make.user
Reorganize Make.inc to do detection earlier
add checked_{add,sub,mul} for BigInt
fix #5935 (rationalize returns curious/incorrect values)

Partially addresses #7501.
Merge branch 'arm-make3' of github.com:JuliaLang/julia into arm-make3

Conflicts:
	Make.inc
julia-mode.el: syntax entry for '/' and '.'

The division operator '/' was missing from the syntax table.  Also it would be better to classify '.' as a punctuation character.
Fix hang/incorrect result for ndigits with b < 0.
Remove debug junk
Add tests for ndigits (issue #8266).
Move negative base check inside ndigits0z and add a test for (unsigned, signed) case.
ndigits: don't take abs(n) if b < 0.
Throw error when bigint ndigits has a negative base.