lli: Factor portable messaging into a new RPCChannel facility

The client and server now use a single unified low-level RPC core built around
LLVM's existing cross-platform abstractions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199947 91177308-0d34-0410-b5e6-96231b3b80d8
Update the X86 assembler for .intel_syntax to produce an error for invalid base
registers in memory addresses that do not match the index register. As it does
for .att_syntax.

rdar://15887380


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199948 91177308-0d34-0410-b5e6-96231b3b80d8
Remove duplicated info on what .text, .data and .bss look like.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199951 91177308-0d34-0410-b5e6-96231b3b80d8