Add missing includes after LLVMCore header cleanup

- conditionally include header only used for expensive check
- have Core.h always include llvm-c/ErrorHandling.h

llvm/include/llvm-c/Core.h

@@ -16,7 +16,9 @@
 #define LLVM_C_CORE_H
 
 #include "llvm-c/Deprecated.h"
+#include "llvm-c/ErrorHandling.h"
 #include "llvm-c/ExternC.h"
+
 #include "llvm-c/Types.h"
 
 LLVM_C_EXTERN_C_BEGIN

llvm/lib/IR/LegacyPassManager.cpp

@@ -28,6 +28,11 @@
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
+
+#ifdef EXPENSIVE_CHECKS
+#include "llvm/IR/StructuralHash.h"
+#endif
+
 using namespace llvm;
 
 // See PassManagers.h for Pass Manager infrastructure overview.