build: added NINJA env to customize ninja binary
Fixes #44286 (closed)
RHEL7 doesn't come with a ninja
binary in the yum package so currently the only way to use ninja is to run ln -s /usr/bin/{ninja-build,ninja}
and modify the system in order to compile with ninja.
Testing
$ sudo mv /usr/bin/{ninja,ninja-build}
$ ./configure --ninja && NINJA=ninja-build make
$ sudo mv /usr/bin/{ninja-build,ninja}
$ ./configure --ninja && make