iostreamlib: add missing cstring header (r.terraflow is compiled properly)

(merge from devbr6, https://trac.osgeo.org/grass/changeset/32760)


git-svn-id: https://svn.osgeo.org/grass/grass/trunk@32761 15284696-431f-4ddb-bdfa-cd5b030d7da7

include/iostream/ami_stream.h

@@ -48,6 +48,7 @@
 #include <errno.h>
 #include <unistd.h>
 
+#include <cstring>
 #include <iostream>
 using namespace std;