build: silence duplicate -lobjc linker warning on Xcode 15+

Add -Wl,-no_warn_duplicate_libraries to the darwin cgo LDFLAGS and allow
it through the cgo flag allowlist via CGO_LDFLAGS_ALLOW in the build
scripts, so the ld-prime duplicate -lobjc note no longer clutters build
output.

scripts/dev-build.sh

@@ -43,6 +43,9 @@ sleep 0.4
 #    --identity flag in v2.
 ARCH="${ARCH:-arm64}"
 echo "[dev-build.sh] building darwin/${ARCH}..."
+# Allow the -Wl,-no_warn_duplicate_libraries flag declared in the darwin cgo
+# files past Go's cgo LDFLAGS allowlist (see activation_policy_darwin.go).
+export CGO_LDFLAGS_ALLOW='-Wl,-no_warn_duplicate_libraries'
 wails build -platform "darwin/${ARCH}" -clean
 
 # 5. Re-sign with the stable dev cert. We invoke sign.sh through env var