In the ExportImport, Fortran, and MacRuntimePath tests the
CMAKE_TEST_MAKEPROGRAM variable is used to pass an explicit request for
a CMAKE_MAKE_PROGRAM value to be used when building the inner projects.
Rename these use cases to CMake_TEST_NESTED_MAKE_PROGRAM.
Pass the CMAKE_TEST_MAKEPROGRAM, if any, to each test at CMake time in
the CMAKE_MAKE_PROGRAM cache entry. Pass the CMAKE_TEST_MAKEPROGRAM
into the ExportImport, Fortran, and MacRuntimePath tests so that they
may do the same for the nested project configurations.
Now "ctest --build-and-test" can get the make program from the test
build tree cache, so drop the explicit --build-makeprogram.