topology: Add option to pass pre-processor definitions

topology: Add option to pass pre-processor definitions

Add a -D switch to be able to pass pre-processor definitions that will
be used to expand arguments in the input config file. This will be
useful to generate multiple topology binaries from the same input config
file with different argument values.

For example: if we had a pipeline config as follows:

Object.Pipeline {
	volume-playback.1 {
		dynamic_pipeline $DYNAMIC_PIPELINE
	}
}

We can define the variable for DYNAMIC_PIPELINE as:

Define {
	DYNAMIC_PIPELINE 0
}

And when pre-processing the conf file pass "-D DYNAMIC_PIPELINE=1" to
override the default value for dynamic_pipeline attribute in the input
conf file.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>