llvm-dwarfdump: type unit dwo support

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198850 91177308-0d34-0410-b5e6-96231b3b80d8
Prototype of skeleton type units for fission

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198851 91177308-0d34-0410-b5e6-96231b3b80d8
Add an "-object-cache-dir=<string>" option to LLI. This option specifies the
root path to which object files managed by the LLIObjectCache instance should be
written. This option defaults to "", in which case objects are cached in the
same directory as the bitcode they are derived from.

The load-object-a.ll test has been rewritten to use this option to support
testing in environments where the test directory is not writable.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198852 91177308-0d34-0410-b5e6-96231b3b80d8
Fix accidental use of the exotic "std::string::back()" method. Turns out it's
new in C++11.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198853 91177308-0d34-0410-b5e6-96231b3b80d8