WINGs: Add optional Pango text layout support

Currently WINGs renders text using Xft directly which does not support
any advanced text layout that is needed for scripts like Arabic or Indic
scripts (or even things like automatic ligature support for Latin
script).

With Pango we also get text fallback for free, so no more square boxes
for characters not supported in the current font (unless no font on the
system supports the specified character, of course).

This patch introduces support for using Pango to render the text (though
its Xft backed), to avoid forcing the additional dependency to everyone
it is made off by default.

Signed-off-by: Carlos R. Mafra <crmafra@gmail.com>

WINGs/WINGs/WINGsP.h

@@ -5,6 +5,9 @@
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 
+#ifdef USE_PANGO
+#include <pango/pango.h>
+#endif
 
 #include <WINGs/WINGs.h>
 
@@ -445,6 +448,10 @@ typedef struct W_Font {
     short y;
     short refCount;
     char *name;
+
+#ifdef USE_PANGO
+    PangoLayout *layout;
+#endif
 } W_Font;
 
 #define W_FONTID(f)		(f)->font->fid