gn2019-06-14tests: Make builds less expensive....The switch to the reduced bootstrap broke build time assumptions made by tests, notably the assumption that GNU-MAKE-BOOT0 was cheap to build. This commit adjusts this to make these tests cheaper. * gnu/packages/bootstrap.scm (%bootstrap-inputs-for-tests): New variable. * guix/tests.scm (gnu-make-for-tests): New variable. * tests/guix-environment.sh: Use GNU-MAKE-FOR-TESTS instead of GNU-MAKE-BOOT0. Remove test with FINDUTILS-BOOT0. * tests/guix-package-net.sh (boot_make): Use GNU-MAKE-FOR-TESTS. * tests/packages.scm ("GNU Make, bootstrap"): Likewise. * tests/profiles.scm ("profile-derivation relative symlinks, two entries"): Likewise. * tests/union.scm (%bootstrap-inputs): Remove. ("union-build"): Use %BOOTSTRAP-INPUTS-FOR-TESTS instead of %BOOTSTRAP-INPUTS. Ludovic Courtès