Fix build compilation with latest LLVM version

rustc LLVM was upgraded in:

rust-lang/rust#30448

This fixes compatibility with API changes

Fixes #38

Author: frewsxcv

plugin/src/afl-llvm-pass.so.cc

@@ -103,7 +103,7 @@ bool AFLCoverage::runOnModule(Module &M) {
     for (auto &BB : F) {
 
       BasicBlock::iterator IP = BB.getFirstInsertionPt();
-      IRBuilder<> IRB(IP);
+      IRBuilder<> IRB(&*IP);
 
       if ((random() % 100) >= inst_ratio) continue;