buildroot

pkg-cmake: reduce output when being silent

Use CMAKE_RULE_MESSAGES and CMAKE_INSTALL_MESSAGE variables to reduce
cmake output when it is a silent build.

[Thomas:
 - use ifneq instead of ifdef
 - remove unneeded else clause
 - also add to the host variant of the configure commands]

Signed-off-by: Fabio Porcedda <fabio.porcedda@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>