Allocator: Name FEX's VMA regions for allocation

Will allow external tools to track how much memory FEX allocates.
Necessary since we can't use traditional memory usage tools to track FEX
memory allocation independently of guest allocations. Plus most tools
like heaptrack hook allocation symbols, which break under jemalloc.

Using this information I can see with Steam loaded with my library that
FEX consumes ~825MB. Total process resident memory is 1204M, accounting
for around 379MB being used by steam itself. This is /relatively/ close
to my desktop running steam at around 261MB. There's a bit of variance
due to what Steam chooses to do at startup.

This tracking will be the first step towards seeing where our memory
usage is going.

FEXCore/Source/Utils/Allocator.cpp

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: MIT
 #include "Utils/Allocator/HostAllocator.h"
+#include "Utils/PrctlUtils.h"
 #include <FEXCore/Utils/Allocator.h>
 #include <FEXCore/Utils/CompilerDefs.h>
 #include <FEXCore/Utils/LogManager.h>
@@ -50,6 +51,10 @@ void* FEX_mmap(void* addr, size_t length, int prot, int flags, int fd, off_t off
     errno = -(uint64_t)Result;
     return (void*)-1;
   }
+
+  if (flags & MAP_ANONYMOUS) {
+    prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, Result, length, "FEXMem");
+  }
   return Result;
 }
 int FEX_munmap(void* addr, size_t length) {