Version 3.0.2 fails to link with any sketch. V3.0.1 works fine.

### Basic Infos

- [ √] This issue complies with the [issue POLICY doc](https://github.com/esp8266/Arduino/blob/master/POLICY.md).
- [ √] I have read the documentation at [readthedocs](https://arduino-esp8266.readthedocs.io/en/latest) and the issue is not addressed there.
- [ √] I have tested that the issue is present in current master branch (aka latest git).
- [ √] I have searched the issue tracker for a similar issue.
- [ ] If there is a stack dump, I have decoded it.
- [ √] I have filled out all fields below.

#### Platform

- Hardware: Wemos d1 mini
- Core Version: 3.0.2
- Development Env: Arduino IDE
- Operating System: Windows 10

### Settings in IDE

- Module: Wemos D1 mini r2
- Flash Mode: unknown
- Flash Size: 4MB
- lwip Variant: [unknown]
- Reset Method: [unknown]
- Flash Frequency: [unknown]
- CPU Frequency: 80Mhz
- Upload Using: SERIAL
- Upload Speed: 921600

### Problem Description
Using Version 3.0.2 of the ESP boards (in the IDE Boards Manager) produces link errors in all sketches, even the example 'blink' sketch. The same sketches compile and link OK for the Uno, but all fail when compiled for the Wemos D1 Mini.

The problem developed in the middle of an ongoing project. I took a dinner break and when I returned, nothing would compile.

Reinstalled Version 3.0.1 and the problem goes away.

### Sketch
As stated in the description, this link error presents for any sketch. The error messages are identical.

### Debug Messages

```
Traceback (most recent call last):

File "C:\Users\steve\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2/tools/elf2bin.py", line 211, in

sys.exit(main())

File "C:\Users\steve\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2/tools/elf2bin.py", line 192, in main

to_addr=4096

File "C:\Users\steve\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2/tools/elf2bin.py", line 187, in wrapper

write_bin(out=out, args=args, **kwargs)

File "C:\Users\steve\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2/tools/elf2bin.py", line 75, in write_bin

[size, addr] = get_segment_size_addr(elf, segment, args.path)

File "C:\Users\steve\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2/tools/elf2bin.py", line 47, in get_segment_size_addr

p = subprocess.Popen([path + '/xtensa-lx106-elf-objdump', '-h', '-j', segment, elf], stdout=subprocess.PIPE, universal_newlines=True )

File "D:\obj\Windows-Release\37win32_Release\msi_python\zip_win32\subprocess.py", line 775, in __init__

File "D:\obj\Windows-Release\37win32_Release\msi_python\zip_win32\subprocess.py", line 1178, in _execute_child

FileNotFoundError: [WinError 2] The system cannot find the file specified

exit status 1

Error compiling for board LOLIN(WEMOS) D1 R2 & mini.
```