mesa-git build script for latest panfrost

[xmixahlx]

panfrost opengl es 3.0 support in git master with PAN_MESA_DEBUG=gles3:
https://www.collabora.com/news-and-blog/...as-landed/

OpenGL ES profile version string: OpenGL ES 3.0 Mesa 20.1.0-devel (git-0bb25e4713)
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00
OpenGL ES profile extensions:
GL_APPLE_texture_max_level, GL_EXT_EGL_image_storage, GL_EXT_blend_minmax,
GL_EXT_color_buffer_float, GL_EXT_compressed_ETC1_RGB8_sub_texture,
GL_EXT_copy_image, GL_EXT_discard_framebuffer, GL_EXT_draw_buffers,
GL_EXT_draw_buffers_indexed, GL_EXT_draw_elements_base_vertex,
GL_EXT_float_blend, GL_EXT_frag_depth, GL_EXT_map_buffer_range,
GL_EXT_multi_draw_arrays, GL_EXT_occlusion_query_boolean,
GL_EXT_read_format_bgra, GL_EXT_sRGB_write_control,
GL_EXT_separate_shader_objects, GL_EXT_shader_integer_mix,
GL_EXT_texture_border_clamp, GL_EXT_texture_format_BGRA8888,
GL_EXT_texture_rg, GL_EXT_texture_sRGB_R8, GL_EXT_texture_sRGB_decode,
GL_EXT_texture_type_2_10_10_10_REV, GL_EXT_unpack_subimage,
GL_KHR_context_flush_control, GL_KHR_debug, GL_KHR_no_error,
GL_KHR_parallel_shader_compile, GL_KHR_texture_compression_astc_ldr,
GL_KHR_texture_compression_astc_sliced_3d, GL_MESA_framebuffer_flip_y,
GL_MESA_shader_integer_functions, GL_NV_draw_buffers,
GL_NV_fbo_color_attachments, GL_NV_read_buffer, GL_NV_read_depth,
GL_NV_read_depth_stencil, GL_NV_read_stencil, GL_OES_EGL_image,
GL_OES_EGL_image_external, GL_OES_EGL_image_external_essl3,
GL_OES_EGL_sync, GL_OES_compressed_ETC1_RGB8_texture, GL_OES_copy_image,
GL_OES_depth24, GL_OES_depth_texture, GL_OES_depth_texture_cube_map,
GL_OES_draw_buffers_indexed, GL_OES_draw_elements_base_vertex,
GL_OES_element_index_uint, GL_OES_fbo_render_mipmap,
GL_OES_get_program_binary, GL_OES_mapbuffer, GL_OES_packed_depth_stencil,
GL_OES_required_internalformat, GL_OES_rgb8_rgba8, GL_OES_stencil8,
GL_OES_surfaceless_context, GL_OES_texture_3D,
GL_OES_texture_border_clamp, GL_OES_texture_float,
GL_OES_texture_float_linear, GL_OES_texture_half_float,
GL_OES_texture_half_float_linear, GL_OES_texture_npot,
GL_OES_texture_stencil8, GL_OES_vertex_array_object,
GL_OES_vertex_half_float