src/pty.c: Fix a compile warning.
src/pty.c: Fix a compile warning.

thestinger/vte-ng,saitoha/vte-sixel,thestinger/vte-ng,saitoha/vte-sixel,flaxandteal/gasket-vte,gloob/vte-copy,asivokon/vte-fx,aligo/vte,pjm0616/vte,rvu95/vte,gloob/vte-copy,asivokon/vte-fx,flaxandteal/gasket-vte,jessevdk/vte,jessevdk/vte,jessevdk/vte,asivokon/vte-fx,aligo/vte,rvu95/vte,aligo/vte,rvu95/vte,pjm0616/vte,asivokon/vte-fx,rvu95/vte,flaxandteal/gasket-vte,pjm0616/vte,thestinger/vte-ng,gloob/vte-copy,jessevdk/vte,flaxandteal/gasket-vte,saitoha/vte-sixel