fix(CI): always use ld64 for the linker on macOS because lld is not available in the CI machine

See also: https://searchfox.org/mozilla-central/rev/e741c34/build/moz.configure/toolchain.configure#1889

Author: Xmader

setup.sh

@@ -63,7 +63,6 @@ sed -i'' -e 's/return JS::GetWeakRefsEnabled() == JS::WeakRefSpecifier::Disabled
 sed -i'' -e 's/return !IsIteratorHelpersEnabled()/return false/' ./js/src/vm/GlobalObject.cpp # forcibly enable iterator helpers
 sed -i'' -e '/MOZ_CRASH_UNSAFE_PRINTF/,/__PRETTY_FUNCTION__);/d' ./mfbt/LinkedList.h # would crash in Debug Build: in `~LinkedList()` it should have removed all this list's elements before the list's destruction
 sed -i'' -e '/MOZ_ASSERT(stackRootPtr == nullptr);/d' ./js/src/vm/JSContext.cpp # would assert false in Debug Build since we extensively use `new JS::Rooted`
-sed -E -i'' -e 's/target.kernel == "Darwin"$/False/' ./build/moz.configure/toolchain.configure # always use ld64 for the linker on macOS because lld is not available in the CI machine
 cd js/src
 mkdir -p _build
 cd _build
@@ -75,6 +74,7 @@ mkdir -p ../../../../_spidermonkey_install/
   --disable-debug-symbols \
   --disable-jemalloc \
   --disable-tests \
+  $(if [[ "$OSTYPE" == "darwin"* ]]; then echo "--enable-linker=ld64"; fi) \
   --enable-optimize 
 make -j$CPUS
 echo "Done building spidermonkey"