8298667: Improved path handling

Reviewed-by: mbalao
Backport-of: 900abc284669d1aadeac8026ad618c9f1dc553a6

Author: Aleksei Voitylov

src/java.base/unix/classes/sun/nio/fs/UnixUriUtils.java

@@ -75,6 +75,10 @@ static Path fromUri(UnixFileSystem fs, URI uri) {
         int pos = 0;
         while (pos < len) {
             char c = p.charAt(pos++);
+            if ((c == '/') && (pos < len) && (p.charAt(pos) == '/')) {
+                // skip redundant slashes
+                continue;
+            }
             byte b;
             if (c == '%') {
                 assert (pos+2) <= len;