https://github.com/ccache/ccache/issues/1815

--- ccache-4.14.1/unittest/test_argprocessing.cpp.orig
+++ ccache-4.14.1/unittest/test_argprocessing.cpp
@@ -35,6 +35,8 @@
 #include <algorithm>
 #include <vector>
 
+#include <unistd.h>
+
 namespace fs = util::filesystem;
 
 using core::Statistic;