WIP: checkpoint geocaching before main integration

modules/core_geocaching/tests/test_crc.cpp

@@ -0,0 +1,10 @@
+#include "sys/crc32.h"
+
+int main()
+{
+    const char vector[] = "123456789";
+    if (sys::crc32(vector, 9) != 0xcbf43926U || sys::crc32(nullptr, 0) != 0) return 1;
+    for (unsigned split = 0; split <= 9; ++split)
+        if (sys::crc32(vector + split, 9 - split, sys::crc32(vector, split)) != 0xcbf43926U) return 2;
+    return 0;
+}