I received a WARN when was configuring GNU make,

When I tried to configure GNU make, I received:

...
WARNING: Your system has neither waitpid() nor wait3().
Without one of these, signal handling is unreliable
You should be aware that running GNU make with -j
could result in erratic behavior.
...

What is that supposed to mean ? my spec:

MinGW and MSYS on Windows 10 (64 bit all)

shell has system mingw64 - environment variable MSYSTEM="MINGW64" - and path to its bin first, before msys/usr/bin, when work's being done

Any sincere useful help is really thanked and appreciated

MinGW is indeed minimum. waitpid() is a unix function. I would simply go with an install of cygwin, if you must have make.

What the error tells you is that the make executable requires run time calls that are not native windows. minGW is there to work natively (meaning as it comes out of Microsoft) in the windows environment. So a lot of GNU stuff won't work correctly in pure minGW. Think of minGW as a gcc compiler instance just for Microsoft C

Read this carefully and decide: MinGW | Minimalist GNU for Windows