clang-analyzer: Fix dead stores in window.c.
clang-analyzer: Fix dead stores in message.c.
clang-analyzer: Fix dead stores in spell.c.
clang-analyzer: Fix dead stores in regexp_nfa.c.
clang-analyzer: Fix dead stores in screen.c.
clang-analyzer: Fix dead stores in search.c.
clang-analyzer: Fix dead stores in arabic.c.
clang-analyzer: Fix dead stores in option.c.
clang-analyzer: Fix dead stores in syntax.c.