Auto merge of #21242 - richo:no-perl, r=brson

There's only one build-critical path in which perl is used, and it was to do a text replacement trivially achievable with sed(1).

I ported the indenter script because it [appears to be used][indenter], but removed check links because it appears to be entirely out of date.

[indenter]: https://github.com/rust-lang/rust/blob/master/src/librustc/util/common.rs#L60-70

Author: bors

Diff for: README.md

@@ -21,7 +21,6 @@ documentation.
 1. Make sure you have installed the dependencies:
     * `g++` 4.7 or `clang++` 3.x
     * `python` 2.6 or later (but not 3.x)
-    * `perl` 5.0 or later
     * GNU `make` 3.81 or later
     * `curl`
     * `git`

Diff for: configure

@@ -617,7 +617,6 @@ putvar CFG_BOOTSTRAP_KEY
 
 step_msg "looking for build programs"
 
-probe_need CFG_PERL        perl
 probe_need CFG_CURLORWGET  curl wget
 probe_need CFG_PYTHON      python2.7 python2.6 python2 python
 
@@ -1375,7 +1374,7 @@ do
 done
 
 # Munge any paths that appear in config.mk back to posix-y
-perl -i.bak -p -e 's@ ([a-zA-Z]):[/\\]@ /\1/@go;' config.tmp
+sed -i.bak -e 's@ \([a-zA-Z]\):[/\\]@ /\1/@g;' config.tmp
 rm -f config.tmp.bak
 
 msg

Diff for: src/etc/check-links.pl

@@ -1,16 +1,19 @@
-#!/usr/bin/perl
-use strict;
-use warnings;
+#!/usr/bin/env python
+import re
+import sys
 
-my $indent = 0;
-while (<>) {
-    if (/^rust: ~">>/) {
-        $indent += 1;
-    }
+indent = 0
+more_re = re.compile(r"^rust: ~\">>")
+less_re = re.compile(r"^rust: ~\"<<")
+while True:
+    line = sys.stdin.readline()
+    if not line:
+        break
 
-    printf "%03d  %s%s", $indent, ("  " x $indent), $_;
+    if more_re.match(line):
+        indent += 1
 
-    if (/^rust: ~"<</) {
-        $indent -= 1;
-    }
-}
+    print "%03d %s%s" % (indent, " " * indent, line.strip())
+
+    if less_re.match(line):
+        indent -= 1