Prior to JDK-8193373 whitebox.cpp had some elfFile usage that was only enabled on Linux:

#ifdef LINUX
#include "utilities/elfFile.hpp"

// Checks that the library libfile has the noexecstack bit set.
WB_ENTRY(jboolean, WB_CheckLibSpecifiesNoexecstack(JNIEnv* env, jobject o, jstring libfile))
  jboolean ret = false;
#ifdef LINUX
...
ret = (jboolean) ElfFile::specifies_noexecstack(lf);
...
#endif
  return ret;
WB_END

But then JDK-8193373 added an unconditional

#include "utilities/elfFile.hpp"

which means there are two include statements for Linux.