File fix.patch of Package libsigv4

https://github.com/riptideslabs/libsigv4/issues/6

diff --git a/sigv4.c b/sigv4.c
index 53442b6..afe2769 100644
--- a/sigv4.c
+++ b/sigv4.c
@@ -10,6 +10,8 @@
 #define AWS_SIGV4_MAX_NUM_QUERY_COMPONENTS 50
 #define HMAC_MAX_MD_CBLOCK 128
 
+#include <strings.h>
+
 int aws_sigv4_empty_str(aws_sigv4_str_t *str)
 {
   return (str == NULL || str->data == NULL || str->len == 0) ? 1 : 0;