[cmake] do all warning suppressions via command line
[cmake] do all warning suppressions via command line

gcc (sometimes) loses diagnostic-ignored pragmas if they are declared in
PCH. the previous approach was to force-include pragma-suppression
header whenever this gcc behaviour causes annoying warnings; however, it
quickly gets out-of-hand. a better approach would be to silence these
warnings down via the command line.

also, added nicely-formatted diagnostics on cmake-configure stage.

vovkos/axl,vovkos/axl,vovkos/axl,vovkos/axl