config.status: Speed up the creation of config headers (about four
times faster on Linux).
* acgeneral.m4 (AC_OUTPUT_HEADERS): Remove the ac_e
family.
Changed ac_uD and ac_dD to `...;t t', instead of `...g'.
Instead of creating `conftest.vals' with both ac_e, ac_d,
and ac_u family, preprocess to strip the trailing spaces, and
create `conftest.defines' with the ac_d family, and then
`conftest.undefs' for the ac_e family.
Break up both `conftest.defines' and `conftest.undefs'. Insert a
top label and a global test for `#defines' and `#undef' before.
Call `conftest.defines' if there are #define in the input.
Call `conftest.undefs'.