CI: Run "make releasetar" regardless of the OS.

Same as in tcpslice.

(cherry picked from commit 166cdc3dfb08744ff3d15a583ca432b3a548d4ff)
diff --git a/build.sh b/build.sh
index 78def6a..e909337 100755
--- a/build.sh
+++ b/build.sh
@@ -86,9 +86,7 @@
 fi
 if [ "$CMAKE" = no ]; then
     system=$(uname -s)
-    if [ "$system" = Darwin ] || [ "$system" = Linux ]; then
-        run_after_echo "make releasetar"
-    fi
+    run_after_echo "make releasetar"
 fi
 if [ "$CIRRUS_CI" = true ]; then
     if [ -n "$LD_LIBRARY_PATH" ]; then