Drop a StringMap.h include, NFC

$ diff -u <(sort thedeps-before.txt) <(sort thedeps-after.txt) \
    | grep '^[-+] ' | sort | uniq -c | sort -nr
    231 -    llvm/include/llvm/ADT/StringMap.h
    171 -    llvm/include/llvm/Support/AllocatorBase.h
    142 -    llvm/include/llvm/Support/PointerLikeTypeTraits.h
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
index 91b1d5a..06d4787 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
+++ b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
@@ -13,6 +13,8 @@
 #ifndef LIB_EXECUTIONENGINE_JITLINK_MACHOLINKGRAPHBUILDER_H
 #define LIB_EXECUTIONENGINE_JITLINK_MACHOLINKGRAPHBUILDER_H
 
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringMap.h"
 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
 
 #include "EHFrameSupportImpl.h"