devtools: fix check of ccache for meson build
devtools: fix check of ccache for meson build

The meson build test fails if ccache is not available.
The use of ccache must be optional.
And if used, the compiler to check is the last word of $CC.

Fixes: e0ae780e6569 ("devtools: test compiler availability only once")

Signed-off-by: Thomas Monjalon <5f50a84c1fa3bcff146405017f36aec1a10a9e38@monjalon.net>
Acked-by: Luca Boccassi <020748dc039465edc3ee6f30c530b21164cdce27@debian.org>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk