nitc: use ccache again
c02e04291807cf97228068cc5b52f453d84ab37b unexpectedly disable ccache.
Since CC is set by default[1], the ?= attempt did never assign anything[2].
The solution is to assign unless if CC is set by another mean.
This can be done thanks to the origin function[3].
[1]: https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html
[2]: https://www.gnu.org/software/make/manual/html_node/Flavors.html
[3]: https://www.gnu.org/software/make/manual/html_node/Origin-Function.html
Signed-off-by: Jean Privat <jean@pryen.org>
nitlanguage / nit.git / commit