Fix compilation problem on iOS/MacOS

Author: saleyn

erts/emulator/beam/erl_nif.c

@@ -79,13 +79,25 @@
 #undef SHMOPEN_USE_POSIX
 #undef USE_ERTS_DLOPEN_MEM
 
+#ifdef HAVE_DLFCN_H
+#include <dlfcn.h>
+#endif
+#ifdef HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+#ifdef HAVE_SYS_MMAN_H
+#include <sys/mman.h>
+#endif
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#ifdef HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #if defined(__linux__)
-#  include <dlfcn.h>
-#  include <fcntl.h>
-#  include <sys/mman.h>
-#  include <sys/stat.h>
-#  include <sys/time.h>
-#  include <unistd.h>
 #  if defined(__linux__)
 #    include <sys/syscall.h>
 #  endif