ENH: add support for ILP64 OpenBLAS (without symbol suffix)

Changing these to support ILP64 blas was missed in gh-15012

Revise the BLAS name mangling to support the general scheme.

Generalize the ILP64 BLAS/LAPACK symbol name handling to deal with
arbitrary prefix/suffix.

The build-time behavior is changed so that HAVE_BLAS_ILP64 and
BLAS_SYMBOL_SUFFIX/PREFIX defines are added to compile options
as appropriate.

Mainly to make autodetection of BLAS/LAPACK easier for downstream
numpy.distutils users, add get_info aliases 'blas_ilp64_opt',
'blas_ilp64_plain_opt', and 'blas64__opt' for any/no/""&"64_"
prefix&suffix, and the same for lapack. (Due to the way system_info
works, each also gets a separate class.)

In addition to openblas64_ which has a fixed suffix, add the (by default
suffixless) openblas_ilp64, which correspond to the most likely cases to
be present.

Distutils code needs to run in different temporary directories, probably
because they create `_configtest.c` files for compiler detection in the
current directory.

Previously, f2py loaded the type mappings from a file ``.f2py_f2cmap``
in current directory, at import time.

Make the file name customizable by adding a ``--f2cmap`` command line
option, and postpone loading the file to f2py.run_main().

Moreover, restore the default type mapping in f2py.run_main() before
loading the customizations, so that multiple calls to f2py.run_main() do
not interfere with each other. (For example, numpy.distutils calls f2py
multiple times in the same process.)

ENH: Add support to sort timedelta64 `NaT` to end of the array

MAINT: follow-up cleanup for blas64 PR