Bootstrapping0: copy all the legacy layouts for the host platform

When cross compiling we are forcing the usage of the resource directory from
the bootstrapping0 compiler to ensure we are picking up the stdlib from
the SDK.
As a result we need to ensure to have legacy layouts for all the
architectures in that folder.

Addresses rdar://98899578

Author: edymtt

stdlib/toolchain/legacy_layouts/CMakeLists.txt

@@ -56,8 +56,15 @@ foreach(sdk ${SWIFT_SDKS})
 endforeach()
 
 if(${BOOTSTRAPPING_MODE} MATCHES "BOOTSTRAPPING.*")
-  # Bootstrapping - level 0
-  add_layout_copying( ${SWIFT_HOST_VARIANT_SDK} ${SWIFT_HOST_VARIANT_ARCH} "0")
+  # The resource dir for bootstrapping0 may be used explicitly
+  # to cross compile for other architectures, so we would need
+  # to have all the legacy layouts in there
+  foreach(arch
+          ${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_ARCHITECTURES}
+          ${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_MODULE_ARCHITECTURES})
+    # Bootstrapping - level 0
+    add_layout_copying( ${SWIFT_HOST_VARIANT_SDK} ${arch} "0")
+  endforeach()
 
   # Bootstrapping - level 1
   add_layout_copying( ${SWIFT_HOST_VARIANT_SDK} ${SWIFT_HOST_VARIANT_ARCH} "1")