mesa: Fix array out-of-bounds access by _mesa_TexGenf.

_mesa_TexGenf calls _mesa_TexGenfv, which uses the params argument
as an array.

src/mesa/main/texgen.c

@@ -211,7 +211,10 @@ _mesa_TexGendv(GLenum coord, GLenum pname, const GLdouble *params )
 static void GLAPIENTRY
 _mesa_TexGenf( GLenum coord, GLenum pname, GLfloat param )
 {
-   _mesa_TexGenfv(coord, pname, &param);
+   GLfloat p[4];
+   p[0] = param;
+   p[1] = p[2] = p[3] = 0.0F;
+   _mesa_TexGenfv(coord, pname, p);
 }