[esan] EfficiencySanitizer base runtime library
Adds the initial version of a runtime library for the new
EfficiencySanitizer ("esan") family of tools. The library includes:
+ Slowpath code via callouts from the compiler instrumentation for
each memory access.
+ Registration of atexit() to call finalization code.
+ Runtime option flags controlled by the environment variable
ESAN_OPTIONS. The common sanitizer flags are supported such as verbosity and log_path.
+ An initial simple test.
Still TODO: common code for libc interceptors and shadow memory mapping,
and tool-specific code for shadow state updating.
Reviewers: eugenis, vitalybuka, aizatsky, filcab
Subscribers: filcab, vkalintiris, kubabrecka, llvm-commits, zhaoqin, kcc
Differential Revision: http://reviews.llvm.org/D19168