## Overview

When using gperf v3.1, the compilation of vte fails because the signature of the generated lookup function differs from the declared one.


## Steps to Reproduce

1) Compile vte with gperf v3.1 installed.


## Actual Results

Compilation fails with

```
vteseq.cc:3426:42: error: call of overloaded 'vteseq_n_lookup(const char*&, int&)' is ambiguous
   seqhandler = vteseq_n_lookup (name, len);
                                          ^
```


## Expected Results

Compilation should not fail.


## Additional Information

Info from gperf NEWS file:

```
* The 'len' parameter of the hash function and of the lookup function is now
  of type 'size_t' instead of 'unsigned int'. This makes it safe to call these
  functions with strings of length > 4 GB, on 64-bit machines.
```

systemd (https://github.com/systemd/systemd/issues/5039) and several other projects encountered the same issue.


## Proposed solution

I already created a patch implementing the solution from systemd: Check the result of gperf with autotools, define a preprocessor variable with the correct data type. If this is to be fixed, I will submit the patch.