Prepare for switching to libziparchive.

Bug: 19765860
Change-Id: I58249d28fbc4975428d0dcac5107d1994c35676c
diff --git a/fastboot/fs.h b/fastboot/fs.h
index 8444081..307772b 100644
--- a/fastboot/fs.h
+++ b/fastboot/fs.h
@@ -3,10 +3,18 @@
 
 #include <stdint.h>
 
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 struct fs_generator;
 
 const struct fs_generator* fs_get_generator(const char *fs_type);
 int fs_generator_generate(const struct fs_generator* gen, int tmpFileNo, long long partSize);
 
+#if defined(__cplusplus)
+}
+#endif
+
 #endif