Add spatch for isc_mem_allocate; it also cannot fail gracefully

cocci/isc_mem_allocate_never_fail.spatch

@@ -0,0 +1,41 @@
+@@
+statement S;
+expression V;
+@@
+
+V = isc_mem_allocate(...);
+- if (V == NULL) S
+
+@@
+type T;
+statement S;
+expression V;
+@@
+
+V = (T *)isc_mem_allocate(...);
+- if (V == NULL) S
+
+@@
+statement S;
+expression V;
+@@
+
+if (V == NULL) V = isc_mem_allocate(...);
+- if (V == NULL) S
+
+@@
+statement S1, S2;
+expression V;
+@@
+
+V = isc_mem_allocate(...);
+- if (V == NULL) S1 else { S2 }
++ S2
+
+@@
+type T;
+expression V, E1, E2;
+@@
+
+- V = (T)isc_mem_allocate(E1, E2);
++ V = isc_mem_allocate(E1, E2);