Fix warnings: window.c: win_rotate(): Np dereference: FP.

Problem    : Dereference of null pointer @ 1268.
Diagnostic : False positive.
Rationale  : Suggested error path implies current window's frame to be
             the only child of its parent, which is ruled out by
             `if (firstwin == lastwin) {` check at the beginning.
Resolution : Assert another child remains after removing current frame.
             Strictly, assert is only needed in false branch of
             conditional, but we add it the same in the true branch to
             reduce reader surprise.
             Several forms of a single assert after
             `if (firstwin == lastwin) {` were tried, but analyzer
             cannot follow implications that way.

0 files changed, 0 insertions, 0 deletions