ck_cc: Add DECONST_PTR and RESTRICT.

DECONST_PTR is a hack to deconstify void pointer values
that is safe in presence of -Wcast-qual. CK_CC_RESTRICT
is restrict qualifier that can be disabled for only
partially C99 compliant compilers.

include/ck_cc.h

@@ -32,6 +32,12 @@
 #include "gcc/ck_cc.h"
 #endif
 
+#ifndef CK_CC_RESTRICT
+#define CK_CC_RESTRICT
+#endif
+
+#define CK_CC_DECONST_PTR(X) ((void *)(uintptr_t)(X))
+
 /*
  * Container function.
  * This relies on (compiler) implementation-defined behavior.

include/gcc/ck_cc.h

@@ -57,6 +57,8 @@
 #define CK_CC_INLINE CK_CC_UNUSED
 #endif
 
+#define CK_CC_RESTRICT restrict
+
 /*
  * Packed attribute.
  */