added a build script

diff --git a/build.sh b/build.sh
new file mode 100755 (executable)
index 0000000..1fd11ba
--- /dev/null
+++ b/build.sh
@@ -0,0 +1,6 @@
+#! /bin/bash
+
+CC="gcc"
+CFLAGS="-O2 -Wall -Wextra -std=c11"
+
+$CC $CFLAGS -c chacha20.c