Add ignore file for macro dir

The contents of the macro directory are too complicated for git.mk to
handle: the contents are filled by autotools and may change between
systems or autotools releases; and we additionally ship our own m4
macros.

To avoid unnecessary noise on the `git status` output we should simply
add an ignore file specifically for the macro directory.

diff --git a/m4/.gitignore b/m4/.gitignore
new file mode 100644 (file)
index 0000000..d425a91
--- /dev/null
+++ b/m4/.gitignore
@@ -0,0 +1,3 @@
+!/ax_prog_cc_for_build.m4
+!/pkg_config_for_build.m4
+*.m4