shared library) and AbsoluteAtoms (proxy atoms for absolute address (e.g. ROM)).
Redesign weak importing as can-be-null-at-runtime and can-be-null-at-build-time.
Add lots of test cases for all the above.

llvm-svn: 151204

llvm-svn: 150547

llvm-svn: 150539

llvm-svn: 149962

llvm-svn: 149432

llvm-svn: 149431

llvm-svn: 149430

llvm-svn: 149429

llvm-svn: 149428

behaivior because it indexes past the end of _contentPool.

llvm-svn: 149427

llvm-svn: 149426

llvm-svn: 149425

First chunk of native object file reader/writer.  The lld-core tool now reads YAML file, links, writes that out as native object format, then reads that native file, then writes the YAML to stdout.  Thus the test suite tests both YAML reading/writing as well as native object file reading/writing.

llvm-svn: 148256

A couple of big refactorings: 1) Move most attributes of Atom down to DefinedAtom, so only atoms representing definitions need to implement them. 2) Remove definitionTentative, definitionWeak, mergeDuplicates, and autoHide.  Replace with merge and interposable attributes. 3) Make all methods on Atom be virtual so that future object file readers can lazily generated attributes

llvm-svn: 147903

llvm-svn: 147799

llvm-svn: 147571

llvm-svn: 147130

llvm-svn: 147105

llvm-svn: 146958

llvm-svn: 146931

llvm-svn: 146844

llvm-svn: 146829

llvm-svn: 146828