Fix uninitialized pointer in view_unmap
Fix uninitialized pointer in view_unmap

Otherwise, sway crashes due to uninitialized pointer
dereference when AddressSanitizer is active.

SirCmpwn/sway,taiyu-len/sway,ascent12/sway,taiyu-len/sway,ascent12/sway,ascent12/sway,1ace/sway,1ace/sway,taiyu-len/sway,1ace/sway