cmake: avoid `@var@` expansion in older CMake versions

Older versions of CMake expanded `@var@` in CMake code, so this could be
expanded at this location rather than the `string(CONFIGURE)` call if
`module` were set inadvertently. Instead, hide the literal `@` symbol
from CMake, but not from the string.

This avoids a CMP0053 warning for projects using Qt5 with a minimum
version set lower than 3.1 and silent bugs with projects explicitly
setting CMP0053 to OLD.

Change-Id: I0e4a86469fdf69b8706387799ab9b17498b8d1ca
Reviewed-by: Stephen Kelly <steveire@gmail.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

0 files changed, 0 insertions, 0 deletions