document iswspace and remove wrongly-included zwsp character

src/ctype/iswspace.c

@@ -2,12 +2,16 @@
 #include <wctype.h>
 #include <ctype.h>
 
+/* Our definition of whitespace is the Unicode White_Space property,
+ * minus non-breaking spaces (U+00A0, U+2007, and U+202F) and script-
+ * specific characters with non-blank glyphs (U+1680 and U+180E). */
+
 int iswspace(wint_t wc)
 {
 	static const wchar_t spaces[] = {
 		' ', '\t', '\n', '\r', 11, 12,  0x0085,
 		0x2000, 0x2001, 0x2002, 0x2003, 0x2004, 0x2005,
-		0x2006, 0x2008, 0x2009, 0x200a, 0x200b,
+		0x2006, 0x2008, 0x2009, 0x200a,
 		0x2028, 0x2029, 0x205f, 0x3000, 0
 	};
 	if (wcschr(spaces, wc)) return 1;