[PPC][PPC64] Improve some llvm-objdump -d -D tests

Various improvement:

Some offsets in disassembly are incorrect after several layout adjustment. Fix them.
llvm-objdump -D should not be used. -D dumps unrelated non-text sections. Replace them with llvm-objdump -d, llvm-readelf -x, etc
Many llvm-objdump -d tests use {{.*}} . Add the option --no-show-raw-insn to avoid check hex bytes.

ppc64-long-branch.s does not need a shared object. Delete it.
Make ppc64-ifunc.s check 2 ifuncs.

Reviewers: ruiu, espindola

Subscribers: emaste, nemanjai, arichardson, kbarton, jsji, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60998

llvm-svn: 358975