Add valgrind uninit check to cmovs output

src/util.h

@@ -69,6 +69,25 @@ static SECP256K1_INLINE void secp256k1_callback_call(const secp256k1_callback *
 #define VERIFY_SETUP(stmt)
 #endif
 
+/* Define `VG_UNDEF` and `VG_CHECK` when VALGRIND is defined  */
+#if !defined(VG_CHECK)
+# if defined(VALGRIND)
+#  include <valgrind/memcheck.h>
+#  define VG_UNDEF(x,y) VALGRIND_MAKE_MEM_UNDEFINED((x),(y))
+#  define VG_CHECK(x,y) VALGRIND_CHECK_MEM_IS_DEFINED((x),(y))
+# else
+#  define VG_UNDEF(x,y)
+#  define VG_CHECK(x,y)
+# endif
+#endif
+
+/* Like `VG_CHECK` but on VERIFY only */
+#if defined(VERIFY)
+#define VG_CHECK_VERIFY(x,y) VG_CHECK((x), (y))
+#else
+#define VG_CHECK_VERIFY(x,y)
+#endif
+
 static SECP256K1_INLINE void *checked_malloc(const secp256k1_callback* cb, size_t size) {
     void *ret = malloc(size);
     if (ret == NULL) {