looks like webp example program failed? 

===

inline ao_instance_t * ao_open (ao_open_t * open)

      | ^~~~~~~

/usr/bin/ld: CMakeFiles/vwebp.dir/examples/vwebp.c.o: warning: relocation against `glutBitmap9By15' in read-only se

make[5]: ingresso nella directory «/home/paz/cinelerra5/cinelerra-5.1/thirdparty/ladspa-0.4.17»

! test -f "amp_1181.xml" || ./makestub.pl "amp_1181.xml" > "amp_1181.c"

/usr/bin/ld: CMakeFiles/vwebp.dir/examples/vwebp.c.o: in function `HandleDisplay':

vwebp.c:(.text+0x551): undefined reference to `glutBitmap9By15'

/usr/bin/ld: vwebp.c:(.text+0x560): undefined reference to `glutBitmapCharacter'

/usr/bin/ld: vwebp.c:(.text+0x5d1): undefined reference to `glutBitmap9By15'

/usr/bin/ld: vwebp.c:(.text+0x5e0): undefined reference to `glutBitmapCharacter'

/usr/bin/ld: vwebp.c:(.text+0x648): undefined reference to `glutBitmap9By15'

/usr/bin/ld: vwebp.c:(.text+0x658): undefined reference to `glutBitmapCharacter'

/usr/bin/ld: CMakeFiles/vwebp.dir/examples/vwebp.c.o: in function `decode_callback':

vwebp.c:(.text+0x835): undefined reference to `glutPostRedisplay'

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check if you have glut (gl utility toolkit?) installed? 

I also can try and disable those examples..