C mode, "benign redefinition" of macros...).

* Manually export private libcaca symbols.

+ Check for sys/times.h and unistd.h.
    + Added calls to AC_C_CONST and AC_C_INLINE.
  * src/time.c src/graphics.c:
    + Fixes for MSVC compilation warnings.
    + Additional sanity checks in the Win32 driver.
  * src/caca.c:
    + Use raw()/noraw() in the curses driver instead of cbreak().
  * msvc/libcaca.sln:
    + Added an MSVC solution.
  * examples/aafire.c:
    + Slightly reduced the maximum cacafire framerate.