clar(clar__assert_equal): do in-bounds check before accessing element

When accessing an array element (or, in these instances, characters in
a string), the check whether the array index is within bounds should
always come before accessing said element.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

t/unit-tests/clar/clar.c

@@ -767,7 +767,7 @@ void clar__assert_equal(
 		if (!is_equal) {
 			if (s1 && s2) {
 				int pos;
-				for (pos = 0; s1[pos] == s2[pos] && pos < len; ++pos)
+				for (pos = 0; pos < len && s1[pos] == s2[pos]; ++pos)
 					/* find differing byte offset */;
 				p_snprintf(buf, sizeof(buf), "'%.*s' != '%.*s' (at byte %d)",
 					len, s1, len, s2, pos);
@@ -803,7 +803,7 @@ void clar__assert_equal(
 		if (!is_equal) {
 			if (wcs1 && wcs2) {
 				int pos;
-				for (pos = 0; wcs1[pos] == wcs2[pos] && pos < len; ++pos)
+				for (pos = 0; pos < len && wcs1[pos] == wcs2[pos]; ++pos)
 					/* find differing byte offset */;
 				p_snprintf(buf, sizeof(buf), "'%.*ls' != '%.*ls' (at byte %d)",
 					len, wcs1, len, wcs2, pos);