LinuxSyscalls: Skip reading ELF files when code caching is disabled

ELF headers were read unconditionally because doing so was assumed to be cheap
(as the guest app would read them anyway shortly after). However, relocation
parsing was added since then, which has less predictable performance due to
crossing page boundaries and reading larger amounts of memory. It might be
possible to make the underlying code more efficient, but until that's done
it's better to skip this logic unless needed.

Closes #5390

Source/Tools/LinuxEmulation/LinuxSyscalls/SyscallsSMCTracking.cpp

@@ -541,9 +541,9 @@ SyscallHandler::TrackMmap(FEXCore::Core::InternalThreadState* Thread, uint64_t a
         Resource->MappedFile->Filename = fextl::string(Tmp, PathLength);
         Resource->MappedFile->FileId = CTX->GetCodeCache().ComputeCodeMapId(Resource->MappedFile->Filename, fd);
 
-        // Read ELF headers if applicable.
+        // Read ELF headers if applicable and needed for code caching.
         // For performance, skip ELF checks if we're not mapping the file header
-        bool CheckForElfFile = (offset == 0);
+        bool CheckForElfFile = (offset == 0) && EnableCodeCaching;
 #if defined(ASSERTIONS_ENABLED) && ASSERTIONS_ENABLED
         CheckForElfFile = true;
 #endif