ninja tool is called to build even for "scons -n"

[mwichmann]

When SCons is called in no-execute mode, and ninja is set up, it builds anyway, which is a bit of a surprise. A snip of a session using a modified version of the example from issue #4342 is pasted here:

ninja-4342]$ find subA -type f
subA/subB/src/filec.c
subA/subB/src/fileb.c
subA/subB/src/filea.c
subA/subB/src/filed.c
subA/subB/SConscript
ninja-4342]$ scons -n
scons: Reading SConscript files ...
Initializing ninja tool... this feature is experimental. SCons internals and all environments will be affected.
SCons running in ninja mode. build.ninja will be generated.
scons: done reading SConscript files.
scons: Building targets ...
Generating: build.ninja
ninja will be run with command line targets:
Executing: /home/mats/.pyenv/versions/venv-system/lib64/python3.11/site-packages/ninja/data/bin/ninja -f /home/mats/github/scons/exp/ninja-4342/build.ninja -j1

[5/5] Archiving subA/subB/libLIB_MANUAL.a
scons: done building targets.
ninja-4342]$ find subA -type f
subA/subB/libLIB_MANUAL.a
subA/subB/src/filec.c
subA/subB/src/filed.o
subA/subB/src/filea.o
subA/subB/src/fileb.c
subA/subB/src/filea.c
subA/subB/src/filed.c
subA/subB/src/filec.o
subA/subB/src/fileb.o
subA/subB/SConscript
ninja-4342]$  

Alternatives mentioned would be to propagate -n to the ninja call, or alternatively, to not call ninja in this mode.

Discord brief discussion link: https://discord.com/channels/571796279483564041/705176473711018024/1100802115418460182