Replaced DBG macro with standard NDEBUG.

[git-p4: depot-paths = "//depot/openwatcom/": change = 37535]
Fixed FDB dumping in debug builds of vi.

[git-p4: depot-paths = "//depot/openwatcom/": change = 37536]
Build fix and a few file descriptions.

[git-p4: depot-paths = "//depot/openwatcom/": change = 37537]