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

To pick up the changes in:

  caabdd0f ("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 <adrian.hunter@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/include/linux/ctype.h

@@ -2,6 +2,8 @@
 #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.
@@ -23,11 +25,6 @@ extern const unsigned char _ctype[];
 #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)
@@ -40,6 +37,16 @@ static inline int __isdigit(int c)
 #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)
 {
 	if (isupper(c))