[ELF][X86] Improve tests

* Add --no-show-raw-insn to llvm-objdump -d tests
* When linking an executable with %t.so, the path %t.so will be recorded
  in the DT_NEEDED entry if %t.so doesn't have DT_SONAME. .dynstr will
  have varying lengths on different systems. Add -soname so that the
  string in .dynstr is of fixed length to make tests more robust.
* Rename i386-tls-initial-exec-local.s to i386-tls-ie-local.s
* Refactor tls-initial-exec-local.s to x86-64-tls-ie-local.s

llvm-svn: 367533