astcenc: Update to 4.4.0

> The 4.4.0 release is a minor release with image quality improvements,
> a small performance boost, a few new quality-of-life features, and a
> few minor fixes for uncommon build configurations.

https://github.com/ARM-software/astc-encoder/releases/tag/4.4.0

modules/astcenc/SCsub

@@ -29,7 +29,6 @@ thirdparty_sources = [
     "astcenc_partition_tables.cpp",
     "astcenc_percentile_tables.cpp",
     "astcenc_pick_best_endpoint_format.cpp",
-    "astcenc_platform_isa_detection.cpp",
     "astcenc_quantization.cpp",
     "astcenc_symbolic_physical.cpp",
     "astcenc_weight_align.cpp",