Adds the -W flag to the pwd call under Win32. This allows directories,

which are munged by sed, such as:
/e/cygwin/opt/diff9c/pgsql/src/test/regress/data/agg.data to be
correctly passed as:
e:/cygwin/opt/diff9c/pgsql/src/test/regress/data/agg.data

FWIW, "fixes" a large (> 20) tests under Win32.

Claudio Natoli