Allow binary names of PATH_MAX length

Required for Guix as otherwise our store paths don't fit here.

diff --git a/src/cmd/scc-cc/posix/cc.c b/src/cmd/scc-cc/posix/cc.c
index 2758d006..319d4b2f 100644
--- a/src/cmd/scc-cc/posix/cc.c
+++ b/src/cmd/scc-cc/posix/cc.c
@@ -43,7 +43,7 @@ enum {
 
 static struct tool {
 	char   cmd[PATH_MAX];
-	char   bin[32];
+	char   bin[PATH_MAX];
 	char  *outfile;
 	struct items args;
 	int    in, out;