Add LTO collision free llvm_mode (#223)

* first new implementation, only works with AFL_DONT_OPTIMIZE

* bug hunting

* interim commit

* finalized LTO non-collision solution

* update documentation

* merge resulted in some problems, fixing these

* added lto env to env check

* fixed llvm weirdness to messes up our instrumentation due CFG rewrite optimizations

* all llvm instrumentation issues have been resolved! :-)

* llvm 9 is required (so far)

* update lto readme

llvm_mode/compare-transform-pass.so.cc

@@ -25,6 +25,7 @@
 #include "llvm/Config/llvm-config.h"
 
 #include "llvm/ADT/Statistic.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/IR/Module.h"