fix ctype macros to cast argument to (unsigned) first

issue reported by nsz, but it's actually not just pedantic. the
functions can take input of any arithmetic type, including floating
point, and the behavior needs to be as if the conversion implicit in
the function call took place.

include/ctype.h

@@ -16,12 +16,12 @@ int   isxdigit(int);
 int   tolower(int);
 int   toupper(int);
 
-#define isalpha(a) ((unsigned)(((a)|32)-'a') < 26)
-#define isdigit(a) ((unsigned)((a)-'0') < 10)
-#define islower(a) ((unsigned)((a)-'a') < 26)
-#define isupper(a) ((unsigned)((a)-'A') < 26)
-#define isprint(a) ((unsigned)((a)-0x20) < 0x5f)
-#define isgraph(a) ((unsigned)((a)-0x21) < 0x5e)
+#define isalpha(a) ((((unsigned)(a)|32)-'a') < 26)
+#define isdigit(a) (((unsigned)(a)-'0') < 10)
+#define islower(a) (((unsigned)(a)-'a') < 26)
+#define isupper(a) (((unsigned)(a)-'A') < 26)
+#define isprint(a) (((unsigned)(a)-0x20) < 0x5f)
+#define isgraph(a) (((unsigned)(a)-0x21) < 0x5e)
 
 
 

include/wctype.h

@@ -36,7 +36,7 @@ wctrans_t wctrans(const char *);
 wctype_t  wctype(const char *);
 
 #undef iswdigit
-#define iswdigit(a) ((unsigned)((a)-L'0') < 10)
+#define iswdigit(a) (((unsigned)(a)-L'0') < 10)
 
 #ifdef __cplusplus
 }