Bugfixes:

• Fix incorrect use of an automatic variable for binding timestamp parameters in Oracle.
• Remove unnecessary lvalue casts.
  These violate the C standard and cause errors on gcc 4.
  Per report from Dominique Legendre.
• Fix lack of support for dropped columns in foreign table.
  oracle_fdw incorrectly assumed that the n-th PostgreSQL column corresponds to the n-th Oracle column. This leads to confusion in the presence of dropped columns, which retain an entry in pg_attribute.
  Per report from Dominique Legendre.
• Fix typo that caused wrong and negative sizes being assumed for longer Oracle columns.
  This led to palloc() errors and Oracle fetch errors.
  Per report from Dominique Legendre.