[MCJIT] Delete the JTIMemoryManager and associated APIs.

This patch removes the old JIT memory manager (which does not provide any
useful functionality now that the old JIT is gone), and migrates the few
remaining clients over to SectionMemoryManager.

http://llvm.org/PR20848



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218316 91177308-0d34-0410-b5e6-96231b3b80d8
[MCJIT] Remove #include of JITMemoryManager that accidentally survived r218316.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218317 91177308-0d34-0410-b5e6-96231b3b80d8
[MCJIT] Remove a few more references to JITMemoryManager that survived r218316.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218318 91177308-0d34-0410-b5e6-96231b3b80d8
[docs] Fixed a typo in Atomics.rst


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218319 91177308-0d34-0410-b5e6-96231b3b80d8