3 fixes for simpletest_raspicam.cpp on raspbian

[marcmerlin]

Hi,

I just checked out the latest version on raspbian/rPi4.
The included example works fine, but when I tried to compile the sample code given on
http://www.uco.es/investiga/grupos/ava/node/40

1. sleep is not found, I had to add
   #include <unistd.h>

2. build is missing -L/opt/vc/lib/. I had to build with
   g++ simpletest_raspicam.cpp -o simpletest_raspicam -I/usr/local/include -L/opt/vc/lib/ -lraspicam -lmmal -lmmal_core -lmmal_util

3. runtime warning

root@rPi4b:~/raspicam/example# ./simpletest_raspicam 
Opening Camera...
Sleeping for 3 secs
/root/raspicam/src/private/private_impl.cpp:179 :Private_Impl::retrieve type is not RASPICAM_FORMAT_IGNORE as it should be
Image saved at raspicam_image.ppm

not sure what the fix should be, but the ppm file works, so that's the important part

[marcmerlin]

I did try to add Camera.setEncoding ( raspicam::RASPICAM_ENCODING_RGB );
but I get

simpletest_raspicam.cpp:22:12: error: ‘class raspicam::RaspiCam’ has no member named ‘setEncoding’; did you mean ‘setMetering’?
     Camera.setEncoding ( raspicam::RASPICAM_ENCODING_RGB );`

I guess the example on http://www.uco.es/investiga/grupos/ava/node/40 is probably against an old more restricted API?