[PATCH] Move asan-coverage into a separate phase.

[Alexey Samsonov]

Looks reasonable to me, coverage certainly deserves a separate pass. Nick, any comments?

================
Comment at: lib/Transforms/Instrumentation/SanitizerCoverage.cpp:104
@@ +103,3 @@
+  Type *IntptrTy;
+  LLVMContext *C;
+
----------------
Looks like this can be `LLVMContext&`

http://reviews.llvm.org/D6152