PowerPC: Initial support for PowerPC64 MCJIT

This patch adds initial support for MCJIT for PPC64-elf-abi. The TOC
relocation and ODP handling is implemented.

It fixes the following ExecutionEngine testcases:

ExecutionEngine/2003-01-04-ArgumentBug.ll
ExecutionEngine/2003-01-04-LoopTest.ll
ExecutionEngine/2003-01-04-PhiTest.ll
ExecutionEngine/2003-01-09-SARTest.ll
ExecutionEngine/2003-01-10-FUCOM.ll
ExecutionEngine/2003-01-15-AlignmentTest.ll
ExecutionEngine/2003-05-11-PHIRegAllocBug.ll
ExecutionEngine/2003-06-04-bzip2-bug.ll
ExecutionEngine/2003-06-05-PHIBug.ll
ExecutionEngine/2003-08-15-AllocaAssertion.ll
ExecutionEngine/2003-08-21-EnvironmentTest.ll
ExecutionEngine/2003-08-23-RegisterAllocatePhysReg.ll
ExecutionEngine/2003-10-18-PHINode-ConstantExpr-CondCode-Failure.ll
ExecutionEngine/simplesttest.ll
ExecutionEngine/simpletest.ll
ExecutionEngine/stubs.ll
ExecutionEngine/test-arith.ll
ExecutionEngine/test-branch.ll
ExecutionEngine/test-call-no-external-funcs.ll
ExecutionEngine/test-cast.ll
ExecutionEngine/test-common-symbols.ll
ExecutionEngine/test-constantexpr.ll
ExecutionEngine/test-fp-no-external-funcs.ll
ExecutionEngine/test-fp.ll
ExecutionEngine/test-global-init-nonzero.ll
ExecutionEngine/test-global.ll
ExecutionEngine/test-loadstore.ll
ExecutionEngine/test-local.ll
ExecutionEngine/test-logical.ll
ExecutionEngine/test-loop.ll
ExecutionEngine/test-phi.ll
ExecutionEngine/test-ret.ll
ExecutionEngine/test-return.ll
ExecutionEngine/test-setcond-fp.ll
ExecutionEngine/test-setcond-int.ll
ExecutionEngine/test-shift.ll

llvm-svn: 166678