BUG: Choose a more unique PY_ARRAY_UNIQUE_SYMBOL in f2py.

In a few exceptional cases where symbols are shared between different
Python modules the use of `PyArray_API` in f2py (fortranobject.h)
conflicts with the regular use of the same symbol in the multiarray
module. Generally the symptom of this conflicting use is a segfault
when importing a f2py'ed module. This occurs because the module init
code somehow overwrites the first element of `PyArray_API` with the
location of `PyArray_API`, causing a crash when
`PyArray_GetNDArrayCVersion` is called.

Closes gh-2521.
Merge pull request #3014 from bfroehle/f2py_unque_symbol

BUG: Choose a more unique PY_ARRAY_UNIQUE_SYMBOL in f2py.