[melodic] Fix Windows build break.

[seanyen]

• Conditionally guard the GCC\CLANG flags.
• Use CMAKE_CXX_STANDARD to set C++14 policy.
• Make the install location more friendly for Windows platform.
  • https://docs.ros.org/api/catkin/html/howto/format1/building_libraries.html#installing
  • https://docs.ros.org/api/catkin/html/howto/format1/building_executables.html#installing
• Avoid the ERROR macro conflicts due to Windows.h gets included in the header inclusion chain.

Verified with https://aka.ms/ros Windows build.

[seanyen]

@SteveMacenski This is ready for review and merge. Thanks!

[SteveMacenski]

LGTM but I mostly leave ROS1 things to Tom. Might be better targeted for a Noetic branch so that there's no breakage on a new release.

[seanyen]

Sounds good. @ayrton04 Let me know what do you think. Perhaps we can have a noetic-devel branch first?

[SteveMacenski]

We'll see what he says first. I'd like to avoid extra branches to try to keep synced if possible.

[ayrton04]

These changes look pretty tame. I think I'd be fine with it going into Melodic.

@SteveMacenski, I've wondered if there's a better model for branch management w.r.t. ROS distros for a while. Maybe we just have a devel branch, and all distros use that until there's an ABI breakage, or we need to EOL a distribution or something?

[ayrton04]

Thank you!

[SteveMacenski]

ROS1’s on its last legs so I’m not super concerned with its management. I think as long as the changes aren’t massive we can keep 1 branch for Kinetic / melodic / noetic. Reducing the maintenance overhead of LTS distro can’t be overstated IMO. Keeping multiple LTS distro branches in sync is a pain so using the same when possible is a big stress reliever.

[ayrton04]

Works for me.

[seanyen]

Thanks for the merge!