ncurses 5.7 - patch 20100327

+ refactor CF_SHARED_OPTS configure macro, making CF_RPATH_HACK more
  reusable.
+ improve configure CF_REGEX, similar fixes.
+ improve configure CF_FIND_LINKAGE, adding add check between system
  (default) and explicit paths, where we can find the entrypoint in the
  given library.
+ add check if Gpm_Open() returns a -2, e.g., for "xterm".  This is
  normally suppressed but can be overridden using $NCURSES_GPM_TERMS.
  Ensure that Gpm_Close() is called in this case.