avoid using funtion isblank() and just use our ISBLANK

macro to provide this functionality on all platforms

ares/configure.ac

@@ -553,7 +553,6 @@ AC_CHECK_MEMBER(struct addrinfo.ai_flags,
 
 
 AC_CHECK_FUNCS( bitncmp \
-                isblank \
                 if_indextoname,
 dnl if found
 [],

ares/setup_once.h

@@ -124,12 +124,8 @@
 #define ISUPPER(x)  (isupper((int)  ((unsigned char)x)))
 #define ISLOWER(x)  (islower((int)  ((unsigned char)x)))
 
-#ifdef HAVE_ISBLANK
-#define ISBLANK(x)  (isblank((int)  ((unsigned char)x)))
-#else
 #define ISBLANK(x)  (int)((((unsigned char)x) == ' ') || \
                           (((unsigned char)x) == '\t'))
-#endif
 
 
 /*