CharUtilsTest#testIsAscii_char loop

The loop currently loops only up to 128, thus testing just positive
return values of CharUtils#isAscii(char). This patch increase the loop
to go over all the possible values of an unsigned byte, thus testing
also negative return values.

src/test/java/org/apache/commons/lang3/CharUtilsTest.java

@@ -219,7 +219,7 @@ public class CharUtilsTest {
         assertTrue(CharUtils.isAscii('\n'));
         assertFalse(CharUtils.isAscii(CHAR_COPY));
 
-        for (int i = 0; i < 128; i++) {
+        for (int i = 0; i < 255; i++) {
             assertEquals(i < 128, CharUtils.isAscii((char) i));
         }
     }