MinGW: Fix compiler warning in merge-recursive
MinGW: Fix compiler warning in merge-recursive

GCC 4.4.0 on Windows does not like the format %zu.  It is quite unlikely,
though, that we need more merge bases than a %d can display, so replace
the %zu by a %d.

Signed-off-by: Johannes Schindelin <53fb8db7833fca1e1746dd8592f61048d350f64c@gmx.de>
Signed-off-by: Steffen Prohaska <0aa497b8475a933a4e2a8b8666146d28b036a2b1@zib.de>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git