Add libusb-1.0 m4 directory and gitignore file.
diff --git a/compat/libusb-1.0/m4/.gitignore b/compat/libusb-1.0/m4/.gitignore
new file mode 100644
index 0000000..464ba5c
--- /dev/null
+++ b/compat/libusb-1.0/m4/.gitignore
@@ -0,0 +1,5 @@
+libtool.m4
+lt~obsolete.m4
+ltoptions.m4
+ltsugar.m4
+ltversion.m4