Configurable client meta-data (#662)

This provide a way to configure snmalloc to provide per object meta-data that is out of band. This can be used to provide different mitigations on top of snmalloc, such as storing memory tags in a compressed form, or provide a miracle pointer like feature.

This also includes a couple of TSAN fixes as it wasn't fully on in CI.

src/test/perf/contention/contention.cc

@@ -154,7 +154,7 @@ void test_tasks(size_t num_tasks, size_t count, size_t size)
   }
 
 #ifndef NDEBUG
-  snmalloc::debug_check_empty<StandardConfig>();
+  snmalloc::debug_check_empty<snmalloc::Alloc::Config>();
 #endif
 };
 

src/test/perf/external_pointer/externalpointer.cc

@@ -47,7 +47,7 @@ namespace test
       alloc.dealloc(objects[i]);
     }
 
-    snmalloc::debug_check_empty<StandardConfig>();
+    snmalloc::debug_check_empty<snmalloc::Alloc::Config>();
   }
 
   void test_external_pointer(xoroshiro::p128r64& r)

src/test/perf/memcpy/memcpy.cc

@@ -1,5 +1,4 @@
-#include "snmalloc/global/memcpy.h"
-
+#include <snmalloc/snmalloc.h>
 #include <test/measuretime.h>
 #include <test/opt.h>
 #include <vector>

src/test/perf/singlethread/singlethread.cc

@@ -60,7 +60,7 @@ void test_alloc_dealloc(size_t count, size_t size, bool write)
     }
   }
 
-  snmalloc::debug_check_empty<StandardConfig>();
+  snmalloc::debug_check_empty<snmalloc::Alloc::Config>();
 }
 
 int main(int, char**)