Update stb_truetype.h

trivial typo

stb_truetype.h

@@ -239,7 +239,7 @@ GLuint ftex;
 void my_stbtt_initfont(void)
 {
    fread(ttf_buffer, 1, 1<<20, fopen("c:/windows/fonts/times.ttf", "rb"));
-   stbtt_BakeFontBitmap(data,0, 32.0, temp_bitmap,512,512, 32,96, cdata); // no guarantee this fits!
+   stbtt_BakeFontBitmap(ttf_buffer,0, 32.0, temp_bitmap,512,512, 32,96, cdata); // no guarantee this fits!
    // can free ttf_buffer at this point
    glGenTextures(1, &ftex);
    glBindTexture(GL_TEXTURE_2D, ftex);