Rollup merge of #132096 - Zalathar:ftp-link, r=jieyouxu

Replace an FTP link in comments with an equivalent HTTPS link

Modern browsers and editors often don't support following FTP links, so using an ordinary web link gives the same result in a more convenient way.

compiler/rustc_data_structures/src/graph/dominators/mod.rs

@@ -2,7 +2,7 @@
 //!
 //! Algorithm based on Loukas Georgiadis,
 //! "Linear-Time Algorithms for Dominators and Related Problems",
-//! <ftp://ftp.cs.princeton.edu/techreports/2005/737.pdf>
+//! <https://www.cs.princeton.edu/techreports/2005/737.pdf>
 //!
 //! Additionally useful is the original Lengauer-Tarjan paper on this subject,
 //! "A Fast Algorithm for Finding Dominators in a Flowgraph"