Suppressing a cmake warning

```
delta:aslam $ cmake --help-policy CMP0026
CMP0026
-------

Disallow use of the LOCATION target property.

CMake 2.8.12 and lower allowed reading the LOCATION target
property (and configuration-specific variants) to
determine the eventual location of build targets.  This relies on the
assumption that all necessary information is available at
configure-time to determine the final location and filename of the
target.  However, this property is not fully determined until later at
generate-time.  At generate time, the $<TARGET_FILE> generator
expression can be used to determine the eventual LOCATION of a target
output.

Code which reads the LOCATION target property can be ported to use the
$<TARGET_FILE> generator expression together with the file(GENERATE)
subcommand to generate a file containing the target location.

The OLD behavior for this policy is to allow reading the LOCATION
properties from build-targets.  The NEW behavior for this policy is to
not to allow reading the LOCATION properties from build-targets.

This policy was introduced in CMake version 3.0.  CMake version
3.0.2 warns when the policy is not set and uses OLD behavior.  Use
the cmake_policy command to set it to OLD or NEW explicitly.
```