Add dlwrap.c to binutils to simulate dlopen/dlsym for gold plugin

dlwrap/dlwrap.h

Index: dlwrap/dlwrap.h
===================================================================
new file mode 100644
--- /dev/null
+++ b/dlwrap/dlwrap.h
@@ -0,0 +1,30 @@
+/* This header is a drop-in replacement for dlfcn.h */
+/* See dlwrap.c for more information */
+
+#ifndef __DLWRAP_H
+#define __DLWRAP_H
+
+#ifdef ENABLE_DLWRAP
+
+#define RTLD_NOW  0x2
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void *pnacl_dlopen(const char *filename, int flag);
+char *pnacl_dlerror(void);
+void *pnacl_dlsym(void *handle, const char *symbol);
+int pnacl_dlclose(void *handle);
+
+#ifdef __cplusplus
+}
+#endif
+
+#define dlopen   pnacl_dlopen
+#define dlerror  pnacl_dlerror
+#define dlsym    pnacl_dlsym
+#define dlclose  pnacl_dlclose
+
+#endif /* ENABLE_DLWRAP */
+#endif /* __DLWRAP_H */