merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/compat/win32/path-utils.c

@@ -0,0 +1,28 @@
+#include "../../git-compat-util.h"
+
+int win32_skip_dos_drive_prefix(char **path)
+{
+	int ret = has_dos_drive_prefix(*path);
+	*path += ret;
+	return ret;
+}
+
+int win32_offset_1st_component(const char *path)
+{
+	char *pos = (char *)path;
+
+	/* unc paths */
+	if (!skip_dos_drive_prefix(&pos) &&
+			is_dir_sep(pos[0]) && is_dir_sep(pos[1])) {
+		/* skip server name */
+		pos = strpbrk(pos + 2, "\\/");
+		if (!pos)
+			return 0; /* Error: malformed unc path */
+
+		do {
+			pos++;
+		} while (*pos && !is_dir_sep(*pos));
+	}
+
+	return pos + is_dir_sep(*pos) - path;
+}