thirdparty.zstd: upgrade to v1.5.7 release, add the local changes to a reusable .patch file (#24611)

vlib/compress/zstd/zstd.c.v

@@ -365,7 +365,7 @@ pub fn version_number() u32 {
 	return C.ZSTD_versionNumber()
 }
 
-// version_string returns runtime library version, like "1.5.8".
+// version_string returns runtime library version, like "1.5.7".
 pub fn version_string() string {
 	return unsafe { tos_clone(C.ZSTD_versionString()) }
 }

vlib/compress/zstd/zstd_d_musl.c.v

@@ -0,0 +1,4 @@
+module zstd
+
+// As MUSL has no `qsort_r()` as GLIBC, so fallback to `qsort()`
+#flag -DZSTD_USE_C90_QSORT