fix prototype of dladdr

this breaks C++ source code in particular.

Change-Id: Ie06b5d31d23b5455e6950c470adc64dd5e7784df
diff --git a/libc/include/dlfcn.h b/libc/include/dlfcn.h
index f84d1d1..7daa8f7 100644
--- a/libc/include/dlfcn.h
+++ b/libc/include/dlfcn.h
@@ -47,7 +47,7 @@
 extern int          dlclose(void*  handle);
 extern const char*  dlerror(void);
 extern void*        dlsym(void*  handle, const char*  symbol);
-extern int          dladdr(void* addr, Dl_info *info);
+extern int          dladdr(const void* addr, Dl_info *info);
 
 enum {
   RTLD_NOW  = 0,