macOS: CONFIG += separate_debug_info does not work with QMAKE_BUNDLE_EXTENSION

The customised bundle extension is ignored, and so the dsymutil call fails.

In the "myproject.pro" file:
CONFIG += plugin no_plugin_name_prefix plugin_bundle hide_symbols separate_debug_info
QMAKE_BUNDLE_EXTENSION = .bundle

Compile output:

mkdir -p myproject.plugin.dSYM/Contents/Resources/DWARF && dsymutil myproject.plugin/Contents/MacOS/myproject --flat -o myproject.plugin.dSYM/Contents/Resources/DWARF/myproject && strip -S myproject.plugin/Contents/MacOS/myproject
error: cannot parse the debug map for 'myproject.plugin/Contents/MacOS/myproject': No such file or directory
make[1]: *** [myproject.bundle/Contents/MacOS/myproject] Error 1
make: *** [sub-myproject-make_first] Error 2