ncurses 6.0 - patch 20151101

ncurses 6.0 - patch 20151101

+ amend change for pkg-config which allows build of pc-files when no
  valid pkg-config library directory was configured to suppress the
  actual install if it is not overridden to a valid directory at
  install time (cf: 20150822).
+ modify editing script which generates resulting.map to work with the
  clang configuration on recent FreeBSD, which gives an error on an
  empty "local" section.
+ fix a spurious "(Part)" message in test/ncurses.c b/B tests due
  to incorrect attribute-masking.