Use hidden towupper in new regex

libc/misc/regex/regex.c

@@ -39,6 +39,7 @@
 #define iswlower __iswlower
 #define iswalnum __iswalnum
 #define towlower __towlower
+#define towupper __towupper
 #define mbsinit __mbsinit
 #include <wchar.h>
 #include <wctype.h>