change GetThemeSysFont() to accept a LOGFONTW* parameter (bug #862)

Closes: https://sourceforge.net/p/mingw-w64/bugs/862/
(cherry picked from commit 12b5d1344c23c5fdba7fb2c771d0476c2220db16)

mingw-w64-headers/include/uxtheme.h

diff --git a/mingw-w64-headers/include/uxtheme.h b/mingw-w64-headers/include/uxtheme.h
index 441cb24..9e876f6 100644
--- a/mingw-w64-headers/include/uxtheme.h
+++ b/mingw-w64-headers/include/uxtheme.h
@@ -239,7 +239,7 @@
 THEMEAPI_(HBRUSH) GetThemeSysColorBrush(HTHEME hTheme,int iColorId);
 THEMEAPI_(WINBOOL) GetThemeSysBool(HTHEME hTheme,int iBoolId);
 THEMEAPI_(int) GetThemeSysSize(HTHEME hTheme,int iSizeId);
-THEMEAPI GetThemeSysFont(HTHEME hTheme,int iFontId,LOGFONT *plf);
+THEMEAPI GetThemeSysFont(HTHEME hTheme,int iFontId,LOGFONTW *plf);
 THEMEAPI GetThemeSysString(HTHEME hTheme,int iStringId,LPWSTR pszStringBuff,int cchMaxStringChars);
 THEMEAPI GetThemeSysInt(HTHEME hTheme,int iIntId,int *piValue);
 THEMEAPI_(WINBOOL) IsThemeActive();