Problem building gstreamer1

[Dan Cîrnaț <dan%alt.md@localhost>]

Hi!

I'm running into errors while building gstreamer1 (Linux AArch64, pkgsrc current)

```
  CC       libgstcontroller_1.0_la-controller-enumtypes.lo
controller-enumtypes.c:10:1: error: expected identifier or '('
\#include "gstinterpolationcontrolsource.h"
^
controller-enumtypes.c:39:9: error: use of undeclared identifier 'GST_LFO_WAVEFORM_SINE'
      { GST_LFO_WAVEFORM_SINE, "GST_LFO_WAVEFORM_SINE", "sine" },
        ^
controller-enumtypes.c:40:9: error: use of undeclared identifier 'GST_LFO_WAVEFORM_SQUARE'
      { GST_LFO_WAVEFORM_SQUARE, "GST_LFO_WAVEFORM_SQUARE", "square" },
        ^
controller-enumtypes.c:41:9: error: use of undeclared identifier 'GST_LFO_WAVEFORM_SAW'
      { GST_LFO_WAVEFORM_SAW, "GST_LFO_WAVEFORM_SAW", "saw" },
        ^
controller-enumtypes.c:42:9: error: use of undeclared identifier 'GST_LFO_WAVEFORM_REVERSE_SAW'
      { GST_LFO_WAVEFORM_REVERSE_SAW, "GST_LFO_WAVEFORM_REVERSE_SAW", "reverse-saw" },
        ^
controller-enumtypes.c:43:9: error: use of undeclared identifier 'GST_LFO_WAVEFORM_TRIANGLE'
      { GST_LFO_WAVEFORM_TRIANGLE, "GST_LFO_WAVEFORM_TRIANGLE", "triangle" },
        ^
6 errors generated.
```

controller-enumtypes.c seems to be autogenerated and contains unnecessary "\" characters:

```
\#include "gstinterpolationcontrolsource.h"
\#include "gstlfocontrolsource.h"
```

A similar bug report for Gentoo: https://bugs.gentoo.org/705974

Anything I can do besides patching the files?

Dan