`elf.sym['read']` gives an incorrect address on Ubuntu 20.04.3 LTS with gcc 9.3.0

## Environment
| Name | Version |
| --- | --- |
| OS | **Ubuntu 20.04.3 LTS (focal)** |
| Pwntools | **4.6.0** |
| gcc | **9.3.0-17ubuntu1~20.04** |
| GNU ld | **2.34** |

I compiled the following program using `gcc 9.3.0` (the default one on Ubuntu 20.04.3 LTS).

```c
#include

int main() {
// no brute forcing
sleep(3);
// exploit me
char buf[4];
read(0, buf, 0x100);
}
```

Here's the problem:
* pwntools: `hex( ELF('./unexploitable').sym['read'] )` gives `0x401054`
* gdb: `read@plt` is at `0x401050`


However, I also compiled this program on Arch Linux using `gcc 11.1.0` and the result is correct.
This erroneous result only happens on **Ubuntu 20.04.3 LTS** with **gcc 9.3.0**

---
The source, makefile and the compiled executable is provided in this zip file: [unexploitable.zip](https://github.com/Gallopsled/pwntools/files/7315310/unexploitable.zip)

Start by reproducing the discrepancy with the attached unexploitable.zip under Ubuntu 20.04.3 LTS, then compare pwntools' elf.sym['read'] result with gdb's read@plt address. Done means the symbol lookup returns the correct address for this executable without regressing the working Arch Linux case.

Written by the indexing model from the issue text.