Cygwin: path: Make some symlinks to /cygdrive/* work.

- Previously, some symbolic links to /cygdrive/* (e.g. /cygdrive/C,
  /cygdrive/./c, /cygdrive//c, etc.) did not work. This patch fixes
  the issue.
  Addresses: https://cygwin.com/pipermail/cygwin/2022-July/251994.html

winsup/cygwin/path.cc

@@ -1929,7 +1929,11 @@ symlink_wsl (const char *oldpath, path_conv &win32_newpath)
      cygdrive prefix is not "/", otherwise suffer random "/mnt" symlinks... */
   if (mount_table->cygdrive_len > 1
       && path_prefix_p (mount_table->cygdrive, oldpath,
-			mount_table->cygdrive_len, false))
+			mount_table->cygdrive_len, false)
+      && (strlen (oldpath + mount_table->cygdrive_len - 1) < 2
+	  || (islower (oldpath[mount_table->cygdrive_len])
+	      && (oldpath[mount_table->cygdrive_len + 1] == '/'
+		  || oldpath[mount_table->cygdrive_len + 1] == '\0'))))
     stpcpy (stpcpy (path_buf, "/mnt"),
 	    oldpath + mount_table->cygdrive_len - 1);
   else

winsup/cygwin/release/3.3.6

@@ -31,3 +31,7 @@ Bug Fixes
   native apps if *.bat or *.cmd is executed directly from cygwin
   shell.
   Addresses: https://cygwin.com/pipermail/cygwin/2022-July/251993.html
+
+- Fix a problem that prevented some symbolic links to /cygdrive/C,
+  /cygdrive/./c, /cygdrive//c, etc. from working.
+  Addresses: https://cygwin.com/pipermail/cygwin/2022-July/251994.html