buildroot

ccache: provide capability to do initial ccache setup

For example, if your project is known to require more space than the
default max cache size, then you might want to increase the cache size
to a suitable amount using the -M (--max-size) option.

The string you specify here is passed verbatim to ccache.  Refer to
ccache documentation for more details.

These initial settings are applied after ccache has been compiled.

Signed-off-by: Danomi Manchego <danomimanchego123@gmail.com>
Reviewed-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Tested-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>