ncurses 6.0 - patch 20160903

ncurses 6.0 - patch 20160903

+ correct 20100515 change for weak signals versus sigprocmask (report
  by Rich Coe).
+ modify misc/Makefile.in to work around OpenBSD "make" which unlike
  all other versions of "make" does not recognize continuation lines
  of comments.
+ amend the last change to CF_C_ENV_FLAGS to move only the
  preprocessor, optimization and warning flags to CPPFLAGS and CFLAGS,
  leaving the residue in CC.  That happens to work for gcc's various
  "model" options, but may require tuning for other compilers (report
  by Sven Joachim).