fix opensolaris build

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@15060 d0543943-73ff-0310-b7d9-9358b9ac24b2

libs/spandsp/src/at_interpreter.c

@@ -40,6 +40,9 @@
 #include <fcntl.h>
 #include <memory.h>
 #include <string.h>
+#if defined(HAVE_STRINGS_H)
+#include <strings.h>
+#endif
 #include <ctype.h>
 #include <assert.h>