Add missing include Host.h in llvm-mc-* fuzzers. NFC.

Fixes build failure in these fuzzers.

llvm/tools/llvm-mc-assemble-fuzzer/llvm-mc-assemble-fuzzer.cpp

@@ -27,6 +27,7 @@
 #include "llvm/MC/SubtargetFeature.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FileUtilities.h"
+#include "llvm/Support/Host.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/TargetRegistry.h"

llvm/tools/llvm-mc-disassemble-fuzzer/llvm-mc-disassemble-fuzzer.cpp

@@ -12,6 +12,7 @@
 #include "llvm-c/Target.h"
 #include "llvm/MC/SubtargetFeature.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Host.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;