cpp: Fix sparse warning

Include cpp.h for the prototype of cpp_exec() in order to fix the
following sparse warning:

  cpp.c:18:5: warning: symbol 'cpp_exec' was not declared. Should it be static?

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

1 files changed, 1 insertions, 0 deletions

diff --git a/cpp.c b/cpp.c
index 30a1404..f6c15af 100644
--- a/cpp.c
+++ b/cpp.c
@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <libgen.h>
 
+#include "cpp.h"
 #include "str.h"
 #include "proc.h"
 #include "xmalloc.h"