GNUmakefile: use tar.xz instead of tar.gz

Also rename "make tgz" to "make source_archive" as it wasn't clear
this only archived the source, not binaries.

D6153 by @JRottm with minor edits

GNUmakefile

@@ -118,7 +118,7 @@ Utilities
      Example
         make icons_geom BLENDER_BIN=/path/to/blender
 
-   * tgz:
+   * source_archive:
      Create a compressed archive of the source code.
 
    * update:
@@ -525,8 +525,8 @@ check_descriptions: .FORCE
 # Utilities
 #
 
-tgz: .FORCE
-	./build_files/utils/build_tgz.sh
+source_archive: .FORCE
+	./build_files/utils/make_source_archive.sh
 
 INKSCAPE_BIN?="inkscape"
 icons: .FORCE

build_files/utils/make_source_archive.sh

@@ -20,7 +20,7 @@ else
 fi
 
 MANIFEST="blender-$VERSION-manifest.txt"
-TARBALL="blender-$VERSION.tar.gz"
+TARBALL="blender-$VERSION.tar.xz"
 
 cd "$blender_srcdir"
 
@@ -54,7 +54,7 @@ echo "OK"
 cd "$blender_srcdir"
 echo -n "Creating archive:            \"$BASE_DIR/$TARBALL\" ..."
 tar --transform "s,^,blender-$VERSION/,g" \
-  --use-compress-program="gzip --best" \
+  --use-compress-program="xz -9" \
   --create \
   --file="$BASE_DIR/$TARBALL" \
   --files-from="$BASE_DIR/$MANIFEST"