Remove unused functions from release builds, and re-enable exception handlings for std lib

[matyalatte]

• Re-enabled exception handlings for the standard library. (054961c)
• Hid symbols for static linked libraries to make MSVC possible to remove unused APIs. (matyalatte/libui-ng@1627edd, Hide symbols for static build c-env-utils#2, Hide symbols for static build tiny-str-match#1)
• Removed some unnecessary function calls from core features of libui. (matyalatte/libui-ng@4a4f6e0)

Exception handling was disabled to reduce the binary size of wxWidgets at old versions of Tuw, but it has been re-enabled as the current binaries are small enough. Also, Windows and macOS binaries have been made smaller by removing some expressions that were preventing compiler optimization.