Fix packing logic error in ```GenImageFontAtlas``` (#2979)
Basic packing algorithm currently follows this order: Copy pixel data -> Move offsetX for current glyph -> Check remaining space for current glyph...
Since X offset already moved according current glyph, remaining space should be checked for next glyph. Because of this, occasionally, current logic causes glyphs wrapping around texture.
Proposed fix accomplishes that by moving offsetX check to the beginning of the loop.