jdk.NativeLibraryEvent hooks all opened regular files

https://mail.openjdk.java.net/pipermail/hotspot-jfr-dev/2020-March/001302.html

We would get multiple jdk.NativeLibrary events from 1 library as below:

```
jdk.NativeLibrary {
   startTime = 16:59:06.621
   name = "/usr/lib64/libc-2.30.so"
   baseAddress = 0x7FDB06ACC000
   topAddress = 0x7FDB06AF1000
}

jdk.NativeLibrary {
   startTime = 16:59:06.621
   name = "/usr/lib64/libc-2.30.so"
   baseAddress = 0x7FDB06AF1000
   topAddress = 0x7FDB06C40000
}

    :

```

In addition, we would get the events even if they are not shared library as below:

```
jdk.NativeLibrary {
   startTime = 16:59:06.621
   name = "/home/ysuenaga/OpenJDK/jdk/build/linux-x86_64-server-fastdebug/images/jdk/lib/server/cl
asses.jsa"
   baseAddress = 0x800000000
   topAddress = 0x800007000
}
```

os::get_loaded_modules_info() has introduced in JDK-8056242, and it says this function is for dll/so/dylibs.
In fact, os::get_loaded_modules_info() uses EnumProcessModules() in Windows.

We should merge same library to one event, and should not hook regular files (not shared library).