Add missing include in test-pwrite.c.

[Ralf Wildenhues]

OK?

Thanks,
Ralf

    Add missing include in test-pwrite.c.
    
    * tests/test-pwrite.c: Include string.h, for strcmp.

diff --git a/tests/test-pwrite.c b/tests/test-pwrite.c
index 549be10..ef80eb2 100644
--- a/tests/test-pwrite.c
+++ b/tests/test-pwrite.c
@@ -24,6 +24,7 @@ SIGNATURE_CHECK (pwrite, ssize_t, (int, const void *, size_t, 
off_t));
 #include <sys/types.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <string.h>
 
 #include "macros.h"