How to compiler dlang code on Apple M1?

[zoujiaqing]

```
dub build --compiler=ldc2 --arch=arm64-apple-macos
     Starting Performing "debug" build using ldc2 for aarch64, 
arm_hardfloat.
     Building taggedalgebraic 0.11.22: building configuration 
[library]
     Building eventcore 0.9.20+commit.4.g6744ae7: building 
configuration [cfrunloop]
     Building server ~master: building configuration [application]
      Linking server
ld: warning: ignoring file 
../../../.dub/packages/taggedalgebraic-0.11.22/taggedalgebraic/.dub/build/library-debug-posix.osx.darwin-aarch64.arm_hardfloat-ldc_v1.30.0-60F6D8BEA34F8F5E792A98EA27B02D2235262A4E0795062F91FA90871411535D/libtaggedalgebraic.a, building for macOS-x86_64 but attempting to link with file built for unknown-arm64
ld: warning: ignoring file 
/opt/homebrew/Cellar/ldc/1.30.0_1/lib/libdruntime-ldc.a, building 
for macOS-x86_64 but attempting to link with file built for 
macOS-arm64
ld: warning: ignoring file 
.dub/build/application-debug-posix.osx.darwin-aarch64.arm_hardfloat-ldc_v1.30.0-7AC1A4B8AFD7D9F59DB01E667A3DCF19DD437F41E741F5937BDCF58FAE6AA922/server.o, building for macOS-x86_64 but attempting to link with file built for unknown-arm64
ld: warning: ignoring file 
../../eventcore/.dub/build/cfrunloop-debug-posix.osx.darwin-aarch64.arm_hardfloat-ldc_v1.30.0-ED6AFABD5E24BB6BCED6FD74F2DE88CF39B648360CE187983206459095D4677D/libeventcore.a, building for macOS-x86_64 but attempting to link with file built for unknown-arm64
ld: warning: ignoring file 
/opt/homebrew/Cellar/ldc/1.30.0_1/lib/libphobos2-ldc.a, building 
for macOS-x86_64 but attempting to link with file built for 
macOS-arm64
Undefined symbols for architecture x86_64:
   "_main", referenced from:
      implicit entry/start for main executable
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to 
see invocation)
Error: /usr/bin/cc failed with status: 1
Error ldc2 failed with exit code 1.
```