MCJIT support for non-function sections.

MCJIT support for non-function sections.

Move to a by-section allocation and relocation scheme. This allows
better support for sections which do not contain externally visible
symbols.

Flesh out the relocation address vs. local storage address separation a
bit more as well. Remote process JITs use this to tell the relocation
resolution code where the code will live when it executes.

The startFunctionBody/endFunctionBody interfaces to the JIT and the
memory manager are deprecated. They'll stick around for as long as the
old JIT does, but the MCJIT doesn't use them anymore.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148258 91177308-0d34-0410-b5e6-96231b3b80d8