tools/cmake: disable cmake script debugger

tools/cmake: disable cmake script debugger

Upstream commit a9a592f96e6498da302f8e968be1db0ad3c32123
("cmake: Add debugger") added a huge amount of code
in order to create a debugging feature for CMakeLists.txt
of other projects. This was added to CMake since 3.27.x.

Unforunately, this new debugger will not build on ARM systems
like arm-linux-gnueabihf (Raspberry Pi 4), and takes up
extra build time for something Openwrt doesn't need,
yet it was enabled by default. (Thanks Microsoft....)

Specifically, it's a failure to link to functions like
__atomic_store_8, __atomic_load_8, __atomic_fetch_add_8, etc.

Let's just disable it.

Someone who really needs this for developing can have CMake
with the debugger on their host machine or manually re-enable it here.

Link: https://gitlab.kitware.com/cmake/cmake/-/issues/21510
Link: https://devblogs.microsoft.com/cppblog/cmake-debugger-allows-you-to-debug-your-cmake-scripts-and-more/
Signed-off-by: Michael Pratt <mcpratt@pm.me>