ref_gl: fix alpha in menu (and anywhere else where triColor4ub is used)

ref_gl/gl_context.c

@@ -513,7 +513,7 @@ ref_interface_t gReffuncs =
 	TriBegin,
 	TriEnd,
 	_TriColor4f,
-	TriColor4ub,
+	_TriColor4ub,
 	TriTexCoord2f,
 	TriVertex3fv,
 	TriVertex3f,

ref_gl/gl_local.h

@@ -577,6 +577,7 @@ void TriTexCoord2f( float u, float v );
 void TriVertex3fv( const float *v );
 void TriVertex3f( float x, float y, float z );
 void _TriColor4f( float r, float g, float b, float a );
+void _TriColor4ub( byte r, byte g, byte b, byte a );
 void TriColor4f( float r, float g, float b, float a );
 void TriColor4ub( byte r, byte g, byte b, byte a );
 void TriBrightness( float brightness );

ref_gl/gl_triapi.c

@@ -131,6 +131,18 @@ void _TriColor4f( float r, float g, float b, float a )
 	pglColor4f( r, g, b, a );
 }
 
+/*
+=============
+_TriColor4f
+
+=============
+*/
+void _TriColor4ub( byte r, byte g, byte b, byte a )
+{
+	pglColor4ub( r, g, b, a );
+}
+
+
 /*
 =============
 TriColor4ub