tsan: de-hardcode MemCount const

[dvyukov]

Summary

Use MemCount instead of hard-coded value 7.

[melver]

compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp

125

This changes from 7 to 8 if I read the enum right.

I guess since the last argument of GetMemoryProfile is size, and mem was already MemCount, this is fine.

compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp

else if (p >= TraceMemBeg() && p < TraceMemEnd())
     mem[MemTrace] += rss;
   else
     mem[MemOther] += rss;
 }
 
 void WriteMemoryProfile(char *buf, uptr buf_size, u64 uptime_ns) {
   uptr mem[MemCount];
   internal_memset(mem, 0, sizeof(mem));
-  GetMemoryProfile(FillProfileCallback, mem, 7);
+  GetMemoryProfile(FillProfileCallback, mem, MemCount);
   auto meta = ctx->metamap.GetMemoryStats();
   StackDepotStats *stacks = StackDepotGetStats();
   uptr nthread, nlive;
   ctx->thread_registry.GetNumberOfThreads(&nthread, &nlive);
   uptr internal_stats[AllocatorStatCount];
   internal_allocator()->GetStats(internal_stats);
   // All these are allocated from the common mmap region.
   mem[MemMmap] -= meta.mem_block + meta.sync_obj + stacks->allocated +