default to number of CPUs for parallel make jobs
The previous default behaviour was to always run 'make -j8', which
can cause C++ build failures on machines which are low on memory.
"Low" being a relative measure; I've seen failures with 4GB of RAM.
Rather than assuming a beefy 8-core box, try to detect the number
of available CPU cores with nproc(1) from GNU coreutils and set
the number of parallel make jobs to the number of CPU cores.
If this command is not available, default to a safe choice: -j1
Note that installing ccache will speed up repeated builds a lot
more than -jX ever will, so falling back to -j1 isn't very bad.
Change-Id: I61c3ea1b3cb5b64eecb08ad6c390594f70cdf785
1 file changed