CMake: Deprecated CMAKE_COMPILER_IS_GNUCXX variable

[Ryanf55]

Bug report

Required Info:

• Operating System:
  • Ubuntu 22.04
• ROS2 Version:
  • Rolling
• Version or commit hash:
  • N/A

Steps to reproduce issue

Just reading the NAV2 CMake source code and NAV2 source code, this variable is deprecated:

https://cmake.org/cmake/help/latest/variable/CMAKE_COMPILER_IS_GNUCXX.html

Expected behavior

Using non-deprecated CMake

Actual behavior

NAV2 is using deprecated variables

Additional information

This should be a quick swap.

[SteveMacenski]

A PR would be appreciated 😄

In the future for things like this that are one-liner changes, you can just submit a PR with this context. No need for a ticket.

[Ryanf55]

You got it