test: Fix main() function prototype Fix compilation error when building for Windows with clang-cl: ../subprojects/libxkbcommon-xkbcommon-1.9.0/test/keysym-unicode.c:11:1: error: return type defaults to 'int' [-Wimplicit-int] ../subprojects/libxkbcommon-xkbcommon-1.9.0/test/keysym-unicode.c:11:1: warning: function declaration isn't a prototype [-Wstrict-prototypes]