CMake: ensure Swift host tools depend on HostCompatibilityLibs target

At the time I implemented #60728, I did not realize that in all the
bootstrapping mode we need to depend on the compatibility libraries we
build -- otherwise when targeting a low deployment target we risk failing
because we are not able to find such libraries.

Addresses rdar://126552386

Author: edymtt

cmake/modules/AddSwift.cmake

@@ -505,8 +505,7 @@ function(_add_swift_runtime_link_flags target relpath_to_lib_dir bootstrapping)
       target_link_directories(${target} PRIVATE "${sdk_dir}")
 
       # A backup in case the toolchain doesn't have one of the compatibility libraries.
-      target_link_directories(${target} PRIVATE
-        "${SWIFTLIB_DIR}/${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_LIB_SUBDIR}")
+      target_link_libraries(${target} PUBLIC HostCompatibilityLibs)
 
       # Include the abi stable system stdlib in our rpath.
       set(swift_runtime_rpath "/usr/lib/swift")
@@ -518,8 +517,7 @@ function(_add_swift_runtime_link_flags target relpath_to_lib_dir bootstrapping)
       target_link_directories(${target} PRIVATE ${bs_lib_dir})
 
       # Required to pick up the built libswiftCompatibility<n>.a libraries
-      target_link_directories(${target} PRIVATE
-        "${SWIFTLIB_DIR}/${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_LIB_SUBDIR}")
+      target_link_libraries(${target} PUBLIC HostCompatibilityLibs)
 
       # At runtime link against the built swift libraries from the current
       # bootstrapping stage.