[llvm] [AVR] Fix parsing & emitting relative jumps (PR #106722)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-x86_64-debian-dylib` running on `gribozavr4` while building `llvm` at step 8 "test-build-unified-tree-check-lld".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/60/builds/6297

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 8 (test-build-unified-tree-check-lld) failure: test (failure)
******************** TEST 'lld :: ELF/avr-reloc.s' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: /b/1/llvm-x86_64-debian-dylib/build/bin/llvm-mc -filetype=obj -triple=avr -mcpu=atmega328p /b/1/llvm-x86_64-debian-dylib/llvm-project/lld/test/ELF/avr-reloc.s -o /b/1/llvm-x86_64-debian-dylib/build/tools/lld/test/ELF/Output/avr-reloc.s.tmp0.o
+ /b/1/llvm-x86_64-debian-dylib/build/bin/llvm-mc -filetype=obj -triple=avr -mcpu=atmega328p /b/1/llvm-x86_64-debian-dylib/llvm-project/lld/test/ELF/avr-reloc.s -o /b/1/llvm-x86_64-debian-dylib/build/tools/lld/test/ELF/Output/avr-reloc.s.tmp0.o
/b/1/llvm-x86_64-debian-dylib/llvm-project/lld/test/ELF/avr-reloc.s:99:1: error: out of range branch target (expected an integer in the range -4096 to 4095)
rjmp 1f + 4094  $ 1:  ; R_AVR_13_PCREL
^
/b/1/llvm-x86_64-debian-dylib/llvm-project/lld/test/ELF/avr-reloc.s:101:1: error: out of range branch target (expected an integer in the range -4096 to 4095)
rjmp 1f + 4096  $ 1:  ; R_AVR_13_PCREL (overflow)
^
/b/1/llvm-x86_64-debian-dylib/llvm-project/lld/test/ELF/avr-reloc.s:103:1: error: out of range branch target (expected an integer in the range -128 to 127)
breq 1f + 126   $ 1:  ; R_AVR_7_PCREL
^

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/106722