misc/cgo/testcarchive: test consistently failing on `ios-arm64-corellium`

[bcmills]

https://build.golang.org/log/b8d0bb75469e93ca77b9c60715c376ef30dd920d:

##### ../misc/cgo/testcarchive
--- FAIL: TestInstall (4.10s)
    carchive_test.go:463: [go tool cgo -objdir /tmp/workdir-host-ios-arm64-corellium-ios/tmp/carchive_test3668726628/_obj3085089307 -exportheader p.h p/p.go]
    carchive_test.go:465: [go install -buildmode=c-archive ./libgo]
    carchive_test.go:465: [/var/root/bin/clangwrap -fPIC -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/workdir-host-ios-arm64-corellium-ios/tmp/go-build3731191633=/tmp/go-build -gno-record-gcc-switches -fno-common -I /tmp/workdir-host-ios-arm64-corellium-ios/tmp/carchive_test3668726628/pkg/ios_arm64_shared/testcarchive -o ./testp1 main.c main_unix.c /tmp/workdir-host-ios-arm64-corellium-ios/tmp/carchive_test3668726628/pkg/ios_arm64_shared/testcarchive/libgo.a]
    carchive_test.go:465: Undefined symbols for architecture arm64:
          "_CFBundleCopyResourceURL", referenced from:
              _x_cgo_init in libgo.a(000005.o)
          "_CFBundleGetMainBundle", referenced from:
              _x_cgo_init in libgo.a(000005.o)
          "_CFBundleGetValueForInfoDictionaryKey", referenced from:
              _x_cgo_init in libgo.a(000005.o)
          "_CFRelease", referenced from:
              _x_cgo_init in libgo.a(000005.o)
          "_CFStringGetCString", referenced from:
              _x_cgo_init in libgo.a(000005.o)
          "_CFURLGetString", referenced from:
              _x_cgo_init in libgo.a(000005.o)
          "___CFConstantStringClassReference", referenced from:
              CFString in libgo.a(000005.o)
              CFString in libgo.a(000005.o)
              CFString in libgo.a(000005.o)
        ld: symbol(s) not found for architecture arm64
        Not signing file
        clang-5.0: error: linker command failed with exit code 1 (use -v to see invocation)
    carchive_test.go:465: exit status 1

[bcmills]

I suspect that this regressed as of CL 463992.

Prior to that CL, (*cmd/dist.tester).extLink reported false for ios-arm64, which caused c-archive mode to appear to be unsupported (https://cs.opensource.google/go/go/+/master:src/cmd/dist/test.go;l=1142-1144;drc=55a33d8877d1bdb8f1b7fb62efe3e38e969f40b1).

The rest of the toolchain did claim to support it (a discrepancy fixed in CL 463992), but apparently it didn't actually work after all.

(attn @ianlancetaylor @golang/ios)

[gopherbot]

Change https://go.dev/cl/464339 mentions this issue: cmd/dist, internal/platform: remove some target modes that fail

[gopherbot]

Change https://go.dev/cl/463752 mentions this issue: cmd/dist,internal/platform: reenable the c-archive build mode on ios