Patch parallel make

[abejgonzalez]

Occasionally, parallel make will silently ignore source file changes. See #377 and https://stackoverflow.com/questions/19822435/multiple-targets-from-one-recipe-and-parallel-execution/. This attempts to address this issue by adding a touch to the targets depending on the INTERMEDIATE value.

This was tested by doing make -j32 on the config./system listed in #377.

Fixes #377

[abejgonzalez]

Note: make 4.3 now supports the group target operator (&:) that is much more elegant. So when we enforce make >= 4.3 we can update this.

https://www.gnu.org/software/make/manual/html_node/Multiple-Targets.html

[jwright6323]

LGTM

[colinschmidt]

Since make 4.3 is so new we should probably wait a while, probably until its in most package managers. If we ask our users to build lots of software from scratch they will get annoyed.

[abejgonzalez]

Since make 4.3 is so new we should probably wait a while, probably until its in most package managers. If we ask our users to build lots of software from scratch they will get annoyed.

I agree. This PR should fix the issue in the meantime.