build: add more support for not needing to set PETSC_DIR yet build with PETSc, also support for GNU make to directly use "make test" instead of "make -f gmakefile.test"

Still needs -include ../petsc

build: add more support for not needing to set PETSC_DIR yet build with PETSc, also support for GNU make to directly use "make test" instead of "make -f gmakefile.test"

Still needs -include ../petscdir.mk in many of the makefiles
Still needs the link for ../petscdir.mk in many directories

GNUMakefile: call legacy makefile recursively instead of including it

GNUMakefile: promote default "all" target; "libs" builds libpetsc*

GNUMakefile: If gnumake < 4.2 prefer makefile wrapper interface over direct gmakefile interface to avoid the following warnings

gmakefile.test:92: arch-ci-linux-cxx-cmplx-pkgs-64idx/tests/testfiles: No such file or directory
gmakefile:67: arch-ci-linux-cxx-cmplx-pkgs-64idx/lib/petsc/conf/files: No such file or directory

Commit-type: testing-fix, feature, usability
Thanks-to: Jed Brown jed@jedbrown.org

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