Fix compilation errors with precompiled headers disabled

aegisub/libaegisub/common/path.cpp

aegisub/libaegisub/common/util.cpp

aegisub/libaegisub/include/libaegisub/util.h

aegisub/libaegisub/unix/io.cpp

aegisub/libaegisub/unix/log.cpp

aegisub/libaegisub/unix/util.cpp

aegisub/reporter/aegisub.h

aegisub/src/command/command.h

aegisub/src/command/edit.cpp

aegisub/src/dialog_fonts_collector.cpp

aegisub/src/dialog_kara_timing_copy.cpp

aegisub/src/dialog_style_manager.cpp

aegisub/src/dialog_timing_processor.cpp

aegisub/src/toolbar.cpp