Fix building with latest LLVM

Bug: b/151314247
Change-Id: Ib10831c42a0c18f86397ed3b6c5d32a578653c89
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/42288
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
diff --git a/src/Reactor/LLVMJIT.cpp b/src/Reactor/LLVMJIT.cpp
index 02ec371..9fcffb3 100644
--- a/src/Reactor/LLVMJIT.cpp
+++ b/src/Reactor/LLVMJIT.cpp
@@ -50,6 +50,7 @@
 #include "llvm/IR/Verifier.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Error.h"
+#include "llvm/Support/Host.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Transforms/Coroutines.h"