Azure RTOS 6.1.5

New features for the 6.1.5 release:
* Added rotation angle definitions.
* Changed pixelmap rotation flag definitions.

Improved logic for 6.1.5 release:
* gx_display_driver_32bpp_rotated_glyph_1bit_draw.c
* gx_display_driver_32bpp_rotated_pixelmap_blend.c
* gx_display_driver_32bpp_rotated_pixelmap_draw.c
* gx_display_driver_32bpp_rotated_pixelmap_rotate.c
* gx_display_driver_8bpp_rotated_horizontal_pixelmap_line_draw.c
* gx_display_driver_generic_rotated_pie_fill.c
* gx_image_reader_pixel_write_callback_set.c
* gx_multi_line_text_view_line_cache_update.c
* gx_rich_text_view_line_info_get.c
* gx_rich_text_view_text_draw.c