[skip ci] Use swift-driver on main scheme

The upstream recently started symlinking swift-driver to swift/swiftc
since swiftlang/swift@6a181fb
so the existence of swift-driver is now mandatory.

We will be able to use swift-driver after swiftlang/swift-driver#1523
is merged.

Author: kateinoigakukun

tools/build/build-toolchain.sh

@@ -48,9 +48,12 @@ else
   echo "Using prebuilt cross compiler..."
   "$TOOLS_BUILD_PATH/install-base-toolchain" --scheme "$SCHEME"
   CROSS_COMPILER_DESTDIR=$PACKAGING_DIR/base-snapshot
-  # FIXME: Remove this once we fixed new swift-driver to use llvm-ar
-  # for WebAssembly target.
-  rm -f "$CROSS_COMPILER_DESTDIR/usr/bin/swift-driver"
+
+  # Only for release/5.9 and release/5.10
+  if [ "$SCHEME" = "release/5.9" ] || [ "$SCHEME" = "release/5.10" ]; then
+    # HACK: Remove swift-driver since the old swift-driver used "ar" instead of "llvm-ar"
+    rm -f "$CROSS_COMPILER_DESTDIR/usr/bin/swift-driver"
+  fi
 fi
 "$TOOLS_BUILD_PATH/build-llvm-tools" --toolchain "$CROSS_COMPILER_DESTDIR"
 

tools/build/package-toolchain

@@ -55,7 +55,9 @@ class PackageAction(Action):
         # $ echo | ./usr/bin/swiftc -target wasm32-unknown-wasi -o /dev/null -
         # The new swift-driver doesn't have this hack, so we remove swift-driver from the toolchain for now.
         swift_driver_path = os.path.join(dist_toolchain_path, 'usr', 'bin', 'swift-driver')
-        if os.path.exists(swift_driver_path):
+        if os.path.exists(swift_driver_path) and \
+                self.options.scheme == 'release/5.9' and \
+                self.options.scheme == 'release/5.10':
             os.remove(swift_driver_path)
 
         wasi_sysroot_path = os.path.join('..', 'build-sdk', 'wasi-sysroot')