tools headers: Update linux/ctype.h with the kernel sources

To pick up the changes in:

caabdd0f59a9771e ("ctype.h: remove duplicate isdigit() helper")

Addressing this perf build warning:

Warning: Kernel ABI header at 'tools/include/linux/ctype.h' differs from latest version at 'include/linux/ctype.h'
diff -u tools/include/linux/ctype.h include/linux/ctype.h

And we need to continue using the combination of:

inline __isdigit()
#define isdigit() __isdigit

When the __has_builtin() thing isn't available, as it is a builtin in
older systems with it as a builtin but with compilers not hacinv
__has_builtin(), rendering the __has_builtin() check useless otherwise.

Cc: Adrian Hunter <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/include/linux/ctype.h

···
 #ifndef _LINUX_CTYPE_H
 #define _LINUX_CTYPE_H
 
+#include <linux/compiler.h>
+
 /*
  * NOTE! This ctype does not handle EOF like the standard C
  * library is required to.
···
 #define isalnum(c)	((__ismask(c)&(_U|_L|_D)) != 0)
 #define isalpha(c)	((__ismask(c)&(_U|_L)) != 0)
 #define iscntrl(c)	((__ismask(c)&(_C)) != 0)
-static inline int __isdigit(int c)
-{
-	return '0' <= c && c <= '9';
-}
-#define isdigit(c)	__isdigit(c)
 #define isgraph(c)	((__ismask(c)&(_P|_U|_L|_D)) != 0)
 #define islower(c)	((__ismask(c)&(_L)) != 0)
 #define isprint(c)	((__ismask(c)&(_P|_U|_L|_D|_SP)) != 0)
···
 
 #define isascii(c) (((unsigned char)(c))<=0x7f)
 #define toascii(c) (((unsigned char)(c))&0x7f)
+
+#if __has_builtin(__builtin_isdigit)
+#define  isdigit(c) __builtin_isdigit(c)
+#else
+static inline int __isdigit(int c)
+{
+	return '0' <= c && c <= '9';
+}
+#define  isdigit(c) __isdigit(c)
+#endif
 
 static inline unsigned char __tolower(unsigned char c)
 {