For purposes of building PETSc in a package manager setting, it would convenient to have a way to turn off the default behavior of not setting CFLAGS, CXXFLAGS, etc. via environment variables.
The reason I bring this up is because in MacPorts (perhaps others) it is impossible to know the full set flags until the package is fully processed. See here for more details: https://lists.macosforge.org/pipermail/macports-dev/2014-October/028279.html At the moment, I patch BuildSystem but was wondering if it'd be worth having a flag (or some other way) to do this.
