changed math operation to be slower but removed chance of interger overflow

Author: aidankeefe2022

src/tools/clu_base64.c

@@ -199,7 +199,7 @@ int wolfCLU_Base64Setup(int argc, char** argv)
         else {
             /* For regular base64 decoding */
             /* Calculate output size */
-            outputSz = (inputSz * 3) / 4 + 1;
+            outputSz = (inputSz / 4) * 3 + (inputSz % 4) * 3 / 4 + 1;
 
             /* Allocate output buffer */
             output = (byte*)XMALLOC(outputSz, HEAP_HINT,