Track /etc/gitconfig

Since WinGit bundles /etc/gitconfig, we better track it.  Also, this
allows us to set sensible defaults, such as symlinks = false and
packSizeLimit = 2g.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

.gitignore

@@ -4,6 +4,5 @@
 /share/git-gui
 /share/gitk
 /share/git-core
-/etc/gitconfig
 /lib/Error.pm
 /lib/Git.pm

etc/gitconfig

@@ -0,0 +1,6 @@
+[core]
+	symlinks = false
+[color]
+	diff = auto
+[pack]
+	packSizeLimit = 2g