[amtk] build: always have a build/ dir available

[Sébastien Wilmet <swilmet src gnome org>]

commit bfa51a3631ae45e60adeb5f2b46f43381baca05b
Author: Sébastien Wilmet <sebastien wilmet gmail com>
Date:   Wed Sep 8 22:18:29 2021 +0200

    build: always have a build/ dir available
    
    It's more convenient for my current needs.

 .gitignore       | 1 -
 build/.gitignore | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/build/.gitignore b/build/.gitignore
new file mode 100644
index 0000000..72e8ffc
--- /dev/null
+++ b/build/.gitignore
@@ -0,0 +1 @@
+*