build: Use HTTPS for all xenbits.xen.org Git repos

Obtaining code over an insecure transport is a terrible idea for
blatently obvious reasons.  Even for non-executable data, insecure
transports are considered deprecated.

This patch enforces the use of secure transports for all xenbits git
repositories.  It was generated with the following shell script:

    git ls-files -z |
    xargs -0 -- sed -Ei -- 's@(git://xenbits\.xen\.org|http://xenbits\.xen\.org/git-http)/@https://xenbits.xen.org/git-http/@g'

All altered links have been tested and are known to work.

Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

scripts/get_maintainer.pl

@@ -1457,7 +1457,7 @@ sub vcs_exists {
 	warn("$P: No supported VCS found.  Add --nogit to options?\n");
 	warn("Using a git repository produces better results.\n");
 	warn("Try latest git repository using:\n");
-	warn("git clone git://xenbits.xen.org/xen.git\n");
+	warn("git clone https://xenbits.xen.org/git-http/xen.git\n");
 	$printed_novcs = 1;
     }
     return 0;