Ports: Add default .gitconfig for Git port

This stops git from asking us to configure a username and email when we
try to commit.

Ports/.gitignore

@@ -2,3 +2,4 @@
 !*/package.sh
 !*/patches
 !*/patches/*
+!*/.gitignore

Ports/git/.gitignore

@@ -0,0 +1 @@
+!default_gitconfig

Ports/git/default_gitconfig

@@ -0,0 +1,3 @@
+[user]
+    email = anon
+    name = anon

Ports/git/package.sh

@@ -11,6 +11,11 @@ build() {
     run make strip
 }
 
+post_install() {
+    mkdir -p "$SERENITY_ROOT"/Build/Root/home/anon
+    cp "$workdir"/../default_gitconfig "$SERENITY_ROOT"/Build/Root/home/anon/.gitconfig
+}
+
 export NO_OPENSSL=1
 export ac_cv_fread_reads_directories=no
 export ac_cv_snprintf_returns_bogus=no