memtest86+: add a .gitignore file

Ignore everything that "make clean" removes.

Change-Id: I5eacaf792756a6d743514f450fbb8aa3439e6b61
Signed-off-by: Ben Gardner <gardner.ben@gmail.com>
Reviewed-on: https://review.coreboot.org/13952
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..9aa8c29
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,7 @@
+*.o
+*.s
+*.iso
+memtest
+memtest.bin
+memtest_shared
+memtest_shared.bin