[SystemZ] Fix IWYU

The file should include <map> instead of relying on the transitive include from
MC/MCPseudoProbe.h.

Author: MaskRay

llvm/lib/Target/SystemZ/SystemZTargetStreamer.h

@@ -12,6 +12,8 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCStreamer.h"
+#include <map>
+#include <utility>
 
 namespace llvm {