Add memory discard message.

This can be used to erase all allocations made within the named memory
pool. The usual use case would be for arena allocators, which allocate
by advancing a pointer and never have to free the memory. There is no
tracking of individual allocations and everything is freed frequently,
by reseting the pointer, for example once per frame.

Since this is used in special-purpose allocators, there is no support
for discarding the memory of the default memory pool.

public/common/TracyProtocol.hpp

@@ -9,7 +9,7 @@ namespace tracy
 
 constexpr unsigned Lz4CompressBound( unsigned isize ) { return isize + ( isize / 255 ) + 16; }
 
-enum : uint32_t { ProtocolVersion = 71 };
+enum : uint32_t { ProtocolVersion = 72 };
 enum : uint16_t { BroadcastVersion = 3 };
 
 using lz4sz_t = uint32_t;