Summary:
Adds the base runtime library for the working set tool.
Adds slowpath code for updating the shadow memory.
To be added in the future:
+ Scan memory and report the total size.
+ Take samples for intermediate values.
Reviewers: aizatsky
Subscribers: kubabrecka, vitalybuka, zhaoqin, kcc, eugenis, llvm-commits
Differential Revision: http://reviews.llvm.org/D20485
llvm-svn: 270650
Derek Bruening