Add the cast to unsigned char

Author: yosuke-wolfssl

src/ecparam/clu_ecparam.c

@@ -154,7 +154,7 @@ int wolfCLU_ecparam(int argc, char** argv)
 
                 /* convert name to upper case */
                 for (i = 0; i < (int)XSTRLEN(name); i++)
-                    name[i] = toupper(name[i]);
+                    name[i] = (char)toupper((unsigned char)name[i]);
 
                 #if 0
                 /* way to get the key size if needed in the future */

src/genkey/clu_genkey_setup.c

@@ -165,7 +165,7 @@ int wolfCLU_genKeySetup(int argc, char** argv)
 
                 /* convert name to upper case */
                 for (i = 0; i < (int)XSTRLEN(name); i++)
-                    name[i] = toupper(name[i]);
+                    name[i] = (char)toupper((unsigned char)name[i]);
             }
         }