nanos6: add patch to use CLOCK_MONOTONIC in CTF

bsc/nanos6/clock-monotonic.patch

@@ -0,0 +1,21 @@
+diff --git a/src/instrument/ctf/ctfapi/CTFClock.hpp b/src/instrument/ctf/ctfapi/CTFClock.hpp
+index 7df821c9..27cf269b 100644
+--- a/src/instrument/ctf/ctfapi/CTFClock.hpp
++++ b/src/instrument/ctf/ctfapi/CTFClock.hpp
+@@ -9,13 +9,9 @@
+ 
+ #include <time.h>
+ 
+-// We prefer CLOCK_MONOTONIC_RAW to prevent dynamic NTF time adjustments.
+-// However, if the system does not support it, we fall back to CLOCK_MONOTONIC
+-
+-#ifdef CLOCK_MONOTONIC_RAW
+-#define CTF_CLOCK CLOCK_MONOTONIC_RAW
+-#else
++// Always use the CLOCK_MONOTONIC clock as it is drift-corrected by NTP,
++// and is the most reliable to compensate changes the oscillator
++// frequency. It is not affected by time jumps.
+ #define CTF_CLOCK CLOCK_MONOTONIC
+-#endif
+ 
+ #endif // CTF_CLOCK_HPP

bsc/nanos6/default.nix

@@ -31,6 +31,8 @@ stdenv.mkDerivation rec {
     sha256 = "17z6gr122cw0l4lsp0qdrdbcl1zcls4i0haxqpj3g60fvjx3fznp";
   };
 
+  patches = [ ./clock-monotonic.patch ];
+
   prePatch = ''
     patchShebangs scripts/generate_config.sh
   '';