Buildfix for lego and bumping common-packages to 0.23.54 (#780)

* fixing build failure

* Bumping common-packages to 0.23.54

libs/core/pxtcore.h

@@ -1,9 +1,16 @@
 #ifndef __PXTCORE_H
 #define __PXTCORE_H
 
+#include <stdio.h>
+
 namespace pxt {
 void dmesg(const char *fmt, ...);
 #define DMESG pxt::dmesg
 }
 
+static inline void itoa(int v, char *dst) {
+
+    snprintf(dst, 30, "%d", v);
+
+}
 #endif

package.json

@@ -39,7 +39,7 @@
     "webfonts-generator": "^0.4.0"
   },
   "dependencies": {
-    "pxt-common-packages": "0.23.45",
+    "pxt-common-packages": "0.23.54",
     "pxt-core": "3.21.7"
   },
   "scripts": {