fmt: pickup change for adding MinGW support

Signed-off-by: Kefu Chai <kchai@redhat.com>

diff --git a/src/fmt b/src/fmt
index 7ad3015f5bc77eda28d52f820e6d89955bf0784a..51bf9cfacb644659e5d9c7e6fe66396726f2f4f4 160000 (submodule)
--- a/src/fmt
+++ b/src/fmt
@@ -1 +1 @@
-Subproject commit 7ad3015f5bc77eda28d52f820e6d89955bf0784a
+Subproject commit 51bf9cfacb644659e5d9c7e6fe66396726f2f4f4