llvmPackages.compiler-rt: dedupe `codesign.patch` 7-12
found with fdupes
```
pkgs/development/compilers/llvm/8/compiler-rt/codesign.patch
pkgs/development/compilers/llvm/10/compiler-rt/codesign.patch
pkgs/development/compilers/llvm/12/compiler-rt/codesign.patch
pkgs/development/compilers/llvm/9/compiler-rt/codesign.patch
pkgs/development/compilers/llvm/7/compiler-rt/codesign.patch
pkgs/development/compilers/llvm/11/compiler-rt/codesign.patch
```