[LLDB] Use llvm::APInt and llvm::APFloat in Scalar and RegisterValue

Eliminated ENABLE_128_BIT_SUPPORT and union ValueData from Scalar.cpp and use llvm::APInt and llvm::APFloat for all integer and floating point types. Also used Scalar in RegisterValue.cpp

Reviewers: tberghammer, ovyalov, clayborg, labath
Subscribers: lldb-commits, nitesh.jain, jaydeep 
Differential: http://reviews.llvm.org/D12100
llvm-svn: 245547