+ fix some strict compiler warnings in ncurses library.
+ modify configure macro CF_HEADER_PATH to not look for variations in
the predefined include directories.
+ improve configure macros CF_GCC_VERSION and CF_GCC_WARNINGS to work
with gcc 4.x's c89 alias, which gives warning messages for cases
where older versions would produce an error.
+ quiet some pedantic gcc warnings.
+ modify _nc_wgetch() to check for a -1 in the fifo, e.g., after a
SIGWINCH, and discard that value, to avoid confusing application
(patch by Eygene Ryabinkin, FreeBSD bin/136223).