Add wapp_str8_lit_ro_initialiser_list to fix gcc compilation errors

src/core/strings/str8/str8.h

@@ -53,6 +53,11 @@ struct str8_list {
 #define wapp_str8_lit_ro(STRING) ((Str8RO){.capacity = sizeof(STRING) - 1, \
                                            .size     = sizeof(STRING) - 1, \
                                            .buf      = (c8 *)STRING})
+// To be used only when initialising a static storage variable in compilers that don't support
+// initialisers with the syntax of wapp_str8_lit_ro
+#define wapp_str8_lit_ro_initialiser_list(STRING) {.capacity = sizeof(STRING) - 1, \
+                                                   .size     = sizeof(STRING) - 1, \
+                                                   .buf      = (c8 *)STRING}
 
 /**
  * Str8 allocated buffers