Fix ARM unwind opcode assembler in several cases.

Changes to ARM unwind opcode assembler:

* Fix multiple .save or .vsave directives.  Besides, the
  order is preserved now.

* For the directives which will generate multiple opcodes,
  such as ".save {r0-r11}", the order of the unwind opcode
  is fixed now, i.e. the registers with less encoding value
  are popped first.

* Fix the $sp offset calculation.  Now, we can use the
  .setfp, .pad, .save, and .vsave directives at any order.

Changes to test cases:

* Add test cases to check the order of multiple opcodes
  for the .save directive.

* Fix the incorrect $sp offset in the test case.  The
  stack pointer offset specified in the test case was
  incorrect.  (Changed test cases: ehabi-mc-section.ll and
  ehabi-mc.ll)

* The opcode to restore $sp are slightly reordered.  The
  behavior are not changed, and the new output is same
  as the output of GNU as.  (Changed test cases:
  eh-directive-pad.s and eh-directive-setfp.s)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183627 91177308-0d34-0410-b5e6-96231b3b80d8
Refine the ARM EHABI test cases.

Since we have ARM unwind directive parser and assembler, we
can check the correctness in two stages:

1. From LLVM assembly (.ll) to ARM assembly (.s)
2. From ARM assembly (.s) to ELF object file (.o)

We already have several "*.s to *.o" test cases.  This CL adds
some "*.ll to *.s" test cases and removes the redundant "*.ll to *.o"
test cases.

New test cases to check "*.ll to *.s" code generator:

- ehabi.ll: Check the correctness of the generated unwind directives.
- section-name.ll: Check the section name of functions.

Removed test cases:

- ehabi-mc-cantunwind.ll
  (Covered by ehabi-cantunwind.ll, and eh-directive-cantunwind.s)
- ehabi-mc-compact-pr0.ll
  (Covered by ehabi.ll, eh-compact-pr0.s, eh-directive-save.s, and
   eh-directive-setfp.s)
- ehabi-mc-compact-pr1.ll
  (Covered by ehabi.ll, eh-compact-pr1.s, eh-directive-save.s, and
   eh-directive-setfp.s)
- ehabi-mc.ll
  (Covered by ehabi.ll, and eh-directive-integrated-test.s)
- ehabi-mc-section-group.ll
  (Covered by section-name.ll, and eh-directive-section-comdat.s)
- ehabi-mc-section.ll
  (Covered by section-name.ll, and eh-directive-section.s)
- ehabi-mc-sh_link.ll
  (Covered by eh-directive-text-section.s, and eh-directive-section.s)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183628 91177308-0d34-0410-b5e6-96231b3b80d8