[CMake] @ONLY and nested variables

[Nico Schlömer]

Hi all,

I would like to use CONFIGURE_PACKAGE_CONFIG_FILE() [1] instead of
CONFIGURE_FILE() for my export configurations. Unfortunately, it seems
that CONFIGURE_PACKAGE_CONFIG_FILE() only supports the @ONLY syntax. I
do use nested variables names in the export configuration, though,
e.g.,
```
SET(${PACKAGE}_LIBS ${${PACKAGE}_LIBRARIES})
```
Any idea how to translate this line into @ONLY syntax? Any other ideas?

Cheers,
Nico


[1] http://www.cmake.org/cmake/help/v3.0/module/CMakePackageConfigHelpers.html