fix: stop relying on system valgrind to build

Author: GuillaumeLagrange

flake.nix

@@ -23,7 +23,6 @@
               setuptools
             ]
           ))
-          valgrind # TODO: Remove this in favor of codspeed's valgrind
         ];
 
       in

packages/core/src/native_core/measurement/measurement.cc

@@ -1,5 +1,5 @@
+#include "callgrind.h"
 #include "measurement.h"
-#include <valgrind/callgrind.h>
 
 namespace codspeed_native {
 namespace Measurement {
@@ -50,4 +50,4 @@ Napi::Object Initialize(Napi::Env env, Napi::Object exports) {
 }
 
 } // namespace Measurement
-} // namespace codspeed_native
+} // namespace codspeed_native