build: resolve 8.3 filename format to long one on Windows

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>

build/git_windows.go

@@ -0,0 +1,26 @@
+package build
+
+import "golang.org/x/sys/windows"
+
+// getLongPathName converts Windows short pathnames to full pathnames.
+// For example C:\Users\ADMIN~1 --> C:\Users\Administrator.
+func getLongPathName(path string) (string, error) {
+	// See https://groups.google.com/forum/#!topic/golang-dev/1tufzkruoTg
+	p, err := windows.UTF16FromString(path)
+	if err != nil {
+		return "", err
+	}
+	b := p // GetLongPathName says we can reuse buffer
+	n, err := windows.GetLongPathName(&p[0], &b[0], uint32(len(b)))
+	if err != nil {
+		return "", err
+	}
+	if n > uint32(len(b)) {
+		b = make([]uint16, n)
+		_, err = windows.GetLongPathName(&p[0], &b[0], uint32(len(b)))
+		if err != nil {
+			return "", err
+		}
+	}
+	return windows.UTF16ToString(b), nil
+}