dym: fix zig cross compilation

[ovadiagal]

The directive #cgo linux LDFLAGS: -Wl,--unresolved-symbols=ignore-all passes the --unresolved-symbols=ignore-all flag to the linker when compiling Go dynamic modules.

This flag is not supported in zig: ziglang/zig#21007.

When trying to bump dynamic-modules-examples to v1.38.0:

------
23.81 error: unsupported linker arg: --unresolved-symbols
23.81 
------
Dockerfile:45
--------------------
  43 |     COPY ./go /build
  44 |     WORKDIR /build
  45 | >>> RUN CC="zig cc -target aarch64-linux-gnu" CXX="zig c++ -target aarch64-linux-gnu" CGO_ENABLED=1 GOARCH=arm64 go build -buildmode=c-shared -o /build/arm64_libgo_module.so .
  46 |     RUN CC="zig cc -target x86_64-linux-gnu" CXX="zig c++ -target x86_64-linux-gnu" CGO_ENABLED=1 GOARCH=amd64 go build -buildmode=c-shared -o /build/amd64_libgo_module.so .
  47 |     
--------------------

Commit Message: dym: fix zig cross compilation
Additional Description:
Risk Level: Low
Testing: N/A
Docs Changes: N/A
Release Notes: N/A
Platform Specific Features:
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[Optional Fixes #Issue]
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Caused by: #44656 was opened by ovadiagal.

see: more, trace.

[ovadiagal]

the alternative i think is to instead make this opt in

Suggested change

	#cgo linux,!zigcc LDFLAGS: -Wl,--unresolved-symbols=ignore-all
	#cgo linux,gnuld LDFLAGS: -Wl,--unresolved-symbols=ignore-all

lmk what u think

[mathetake]

hmm. is the issue specific non gnuld is what you are saying? that's weird though !zigcc feels also weird...

[mathetake]

hmm i think we can drop the linux LDFLAGS in the first place I think? the linker flag is only necessary for macos i believe.

[mathetake]

(that's why it's been working before v1.38)

[ovadiagal]

updated to drop the entire line

[agrawroh]

@mathetake Could you please take a look at this one?