test_library_directory_values_can_look_like_modes passed -L -E as mode
flags, so check_modes took the -E for a preprocessing mode and dropped -c.
Its control commands linked an executable with each compiler, which on
the Windows runner goes through link.exe; the case took about twice as
long as its -I -E counterpart and timed out in 6 Windows CI jobs. The
-L -E pair now goes through configure like the include directory case,
so the control only compiles. The command check_compile checks is the
same, since it drops -c.
test_response_options_compile_without_changing_build_outputs ran 30
check_compile invocations in one case. Its six response files are now
checked by three cases of two.
dantdmdarealguy