[PATCH 4/8] Addition of clang nullability qualifiers.

[Sebastian Huber <sebastian.huber@embedded-brains.de>]

From: pfg <pfg@FreeBSD.org>

Add two new qualifiers for use by the static checkers:

_Nonnull
The _Nonnull nullability qualifier indicates that null is not a meaningful
value for a value of the _Nonnull pointer type.

_Nullable
The _Nullable nullability qualifier indicates that a value of the
_Nullable pointer type can be null.

These were introduced in Clang 3.7. For more information, see:
http://clang.llvm.org/docs/AttributeReference.html#nonnull

We add these now without using them so that the GCC ports have time to
pick up the header change.

Hinted by:	Android Bionic libc [1]
Also seen in:	Apple's Libc-1158.20.4

[1]
https://github.com/android/platform_bionic/commit/baa2a973bd776a51bb05a8590ab05d86eea7b321
---
 newlib/libc/include/sys/cdefs.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/newlib/libc/include/sys/cdefs.h b/newlib/libc/include/sys/cdefs.h
index 68172ad..ad23232 100644
--- a/newlib/libc/include/sys/cdefs.h
+++ b/newlib/libc/include/sys/cdefs.h
@@ -645,6 +645,14 @@
 #endif
 
 /*
+ * Nullability qualifiers: currently only supported by Clang.
+ */
+#if !(defined(__clang__) && __has_feature(nullability))
+#define	_Nonnull
+#define	_Nullable
+#endif
+
+/*
  * Type Safety Checking
  *
  * Clang provides additional attributes to enable checking type safety
-- 
1.8.4.5