Add Go functions for git_config_find_* functions

ConfigFindGlobal -> git_config_find_global
ConfigFindSystem -> git_config_find_system
ConfigFindXDG    -> git_config_find_xdg

config.go

@@ -35,14 +35,14 @@ const (
 )
 
 type ConfigEntry struct {
-	Name string
+	Name  string
 	Value string
 	Level ConfigLevel
 }
 
 func newConfigEntryFromC(centry *C.git_config_entry) *ConfigEntry {
 	return &ConfigEntry{
-		Name: C.GoString(centry.name),
+		Name:  C.GoString(centry.name),
 		Value: C.GoString(centry.value),
 		Level: ConfigLevel(centry.level),
 	}
@@ -74,7 +74,6 @@ func (c *Config) AddFile(path string, level ConfigLevel, force bool) error {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 
-
 	ret := C.git_config_add_file_ondisk(c.ptr, cpath, C.git_config_level_t(level), cbool(force))
 	if ret < 0 {
 		return MakeGitError(ret)
@@ -130,7 +129,6 @@ func (c *Config) LookupString(name string) (string, error) {
 	return C.GoString(ptr), nil
 }
 
-
 func (c *Config) LookupBool(name string) (bool, error) {
 	var out C.int
 	cname := C.CString(name)
@@ -234,7 +232,6 @@ func (c *Config) SetInt32(name string, value int32) (err error) {
 	cname := C.CString(name)
 	defer C.free(unsafe.Pointer(cname))
 
-
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 
@@ -368,3 +365,48 @@ func (iter *ConfigIterator) Free() {
 	runtime.SetFinalizer(iter, nil)
 	C.free(unsafe.Pointer(iter.ptr))
 }
+
+func ConfigFindGlobal() (string, error) {
+	var buf C.git_buf
+	defer C.git_buf_free(&buf)
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ret := C.git_config_find_global(&buf)
+	if ret < 0 {
+		return "", MakeGitError(ret)
+	}
+
+	return C.GoString(buf.ptr), nil
+}
+
+func ConfigFindSystem() (string, error) {
+	var buf C.git_buf
+	defer C.git_buf_free(&buf)
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ret := C.git_config_find_system(&buf)
+	if ret < 0 {
+		return "", MakeGitError(ret)
+	}
+
+	return C.GoString(buf.ptr), nil
+}
+
+func ConfigFindXDG() (string, error) {
+	var buf C.git_buf
+	defer C.git_buf_free(&buf)
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ret := C.git_config_find_xdg(&buf)
+	if ret < 0 {
+		return "", MakeGitError(ret)
+	}
+
+	return C.GoString(buf.ptr), nil
+}