avdevice/oss_audio: Add #if HAVE_UNISTD_H around  #include <unistd.h>

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/vf_drawtext: Add #if HAVE_UNISTD_H around  #include <unistd.h>

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avutil/cpu: Use HAVE_UNISTD_H instead of HAVE_SYSCONF for #include <unistd.h>

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/crystalhd: Add #if HAVE_UNISTD_H around  #include <unistd.h>

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>