The following code would crash the previous version when calling MemFree:

	// 53 * A
        const char maliciousBase64Input[] = "AAAAAAAAAAAAAAAAAAAAAAAA"
		"AAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
        int decodedSize = 0;
        unsigned char *decodedData = DecodeDataBase64(
		maliciousBase64Input, &decodedSize);
        if (decodedData) {
		MemFree(decodedData);
        }

The reason is a lack of array bound checks in the decoding loop, which
corrupted here the heap (though this is platform dependent).

Adding the bound checks here prevents the memory corruption.

Tested with encoding random data of sizes 0-1023 and comparing it
with the decoded result.

This reverts commit b5e25916fc.

ADDED: `UpdateSourceMetadata()`

Reviewed star used, aligned with empty star and examples header

The example is not following examples conventions and it will be moved to `others` with a new name

This example was POSIX only and had some special requirements for web, it made it more difficult to be managed from collection standard examples format.

It will be re-added in the `others` category, that is not processed for web.