mismatch between toolchain configured by configure vs ghc-toolchain
## Summary
Configure time warning is printed that says I should report a bug.
```
configure: WARNING:
There are some differences between the toolchain configured by "configure" (hadrian/cfg/default.target) and the toolchain configured by the "ghc-toolchain" program (hadrian/cfg/default.target.ghc-toolchain).
15,16c15,16
< , tgtCCompiler = Cc {ccProgram = Program { prgPath = "gcc" , prgFlags = [] }}
< , tgtCxxCompiler = Cxx {cxxProgram = Program { prgPath = "g++" , prgFlags = [] }}
---
> , tgtCCompiler = Cc {ccProgram = Program { prgPath = "gcc" , prgFlags = ["-mbranch-protection=standard"] }}
> , tgtCxxCompiler = Cxx {cxxProgram = Program { prgPath = "g++" , prgFlags = ["-mbranch-protection=standard"] }}
Don't worry! This won't affect your ghc in any way.
However, in a near future, we will move to configuring toolchains with "ghc-toolchain" by default, so you might have discovered a future bug.
In light of it, if you've spotted this difference, please report a GHC bug at https://www.haskell.org/ghc/reportabug
```
## Steps to reproduce
```bash
./boot
./configure
```
## Expected behavior
No warning.
## Environment
```bash
export CFLAGS="-mbranch-protection=standard"
export CXXFLAGS="$CFLAGS"
export LD="/home/bill/bin/mylld"
```
* GHC version used:
HEAD: 278a53ee6
Optional:
* Operating System:
- Fedora 40
* System Architecture:
- AArch64
issue