Improve build: add <unistd.h> and use -O2 instead of -O3

(Nobody should use -O3. It just makes bad inlining decisions).

1 files changed, 1 insertions, 0 deletions

diff --git a/cache.h b/cache.h
index eab355da5d..a67b79e97f 100644
--- a/cache.h
+++ b/cache.h
@@ -1,6 +1,7 @@
 #ifndef CACHE_H
 #define CACHE_H
 
+#include <unistd.h>
 #include <stdio.h>
 #include <sys/stat.h>
 #include <fcntl.h>