Fix for PR14824: "Optimization arm_ldst_opt inserts newly generated instruction vldmi...

Fix for PR14824: "Optimization arm_ldst_opt inserts newly generated instruction vldmia at incorrect position".
Patch introduces memory operands tracking in ARMLoadStoreOpt::LoadStoreMultipleOpti. For each register it keeps the order of load operations as it was before optimization pass.
It is kind of deep improvement of fix proposed by Hao: http://llvm.org/bugs/show_bug.cgi?id=14824#c4
But it also tracks conflicts between different register classes (e.g. D2 and S5).
For more details see:
Bug description: http://llvm.org/bugs/show_bug.cgi?id=14824
LLVM Commits discussion:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20130311/167936.html
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20130318/168688.html
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20130325/169376.html
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20130401/170238.html

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178851 91177308-0d34-0410-b5e6-96231b3b80d8