[mod_verto] Fix scan-build warnings in swig and enable scan-build on Drone

src/mod/endpoints/mod_verto/mcast/MCAST.i

@@ -1,3 +1,13 @@
+%begin %{
+#ifdef __clang_analyzer__
+#include <string.h>
+static int mystrcmp (const char *a, const char *b) {
+    return a == b ? 0 : !a ? -1 : !b ? 1 : strcmp(a, b);
+}
+#define strcmp mystrcmp
+#endif
+%}
+
 %{
 #include "mcast.h"
 #include "mcast_cpp.h"

src/mod/endpoints/mod_verto/mcast/mcast_wrap.cpp

@@ -8,6 +8,15 @@
  * interface file instead.
  * ----------------------------------------------------------------------------- */
 
+#ifdef __clang_analyzer__
+#include <string.h>
+static int mystrcmp (const char *a, const char *b) {
+    return a == b ? 0 : !a ? -1 : !b ? 1 : strcmp(a, b);
+}
+#define strcmp mystrcmp
+#endif
+
+
 
 #ifndef SWIGPERL
 #define SWIGPERL