test: remove errchk, the perl script

gc tests do not depend on errchk.

Fixes #25669

Change-Id: I99eb87bb9677897b9167d4fc9a6321fa66cd9116
Reviewed-on: https://go-review.googlesource.com/115955Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

test/errchk

-#!/usr/bin/env perl
-# Copyright 2009 The Go Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style
-# license that can be found in the LICENSE file.
-
-# This script checks that the compilers emit the errors which we expect.
-# Usage: errchk COMPILER [OPTS] SOURCEFILES.  This will run the command
-# COMPILER [OPTS] SOURCEFILES.  The compilation is expected to fail; if
-# it succeeds, this script will report an error.  The stderr output of
-# the compiler will be matched against comments in SOURCEFILES.  For each
-# line of the source files which should generate an error, there should
-# be a comment of the form // ERROR "regexp".  If the compiler generates
-# an error for a line which has no such comment, this script will report
-# an error.  Likewise if the compiler does not generate an error for a
-# line which has a comment, or if the error message does not match the
-# <regexp>.  The <regexp> syntax is Perl but its best to stick to egrep.
-
-use POSIX;
-
-my $exitcode = 1;
-
-if(@ARGV >= 1 && $ARGV[0] eq "-0") {
-	$exitcode = 0;
-	shift;
-}
-
-if(@ARGV < 1) {
-	print STDERR "Usage: errchk COMPILER [OPTS] SOURCEFILES\n";
-	exit 1;
-}
-
-# Grab SOURCEFILES
-foreach(reverse 0 .. @ARGV-1) {
-	unless($ARGV[$_] =~ /\.(go|s)$/) {
-		@file = @ARGV[$_+1 .. @ARGV-1];
-		last;
-	}
-}
-
-# If no files have been specified try to grab SOURCEFILES from the last
-# argument that is an existing directory if any
-unless(@file) {
-    foreach(reverse 0 .. @ARGV-1) {
-        if(-d $ARGV[$_]) {
-            @file = glob($ARGV[$_] . "/*.go");
-            last;
-        }
-    }
-}
-
-foreach $file (@file) {
-	open(SRC, $file) || die "BUG: errchk: open $file: $!";
-	$src{$file} = [<SRC>];
-	close(SRC);
-}
-
-# Run command
-$cmd = join(' ', @ARGV);
-open(CMD, "exec $cmd </dev/null 2>&1 |") || die "BUG: errchk: run $cmd: $!";
-
-# gc error messages continue onto additional lines with leading tabs.
-# Split the output at the beginning of each line that doesn't begin with a tab.
-$out = join('', <CMD>);
-@out = split(/^(?!\t)/m, $out);
-
-close CMD;
-
-# Remove lines beginning with #, printed by go command to indicate package.
-@out = grep {!/^#/} @out;
-
-if($exitcode != 0 && $? == 0) {
-	print STDERR "BUG: errchk: command succeeded unexpectedly\n";
-	print STDERR @out;
-	exit 0;
-}
-
-if($exitcode == 0 && $? != 0) {
-	print STDERR "BUG: errchk: command failed unexpectedly\n";
-	print STDERR @out;
-	exit 0;
-}
-
-if(!WIFEXITED($?)) {
-	print STDERR "BUG: errchk: compiler crashed\n";
-	print STDERR @out, "\n";
-	exit 0;
-}
-
-sub bug() {
-	if(!$bug++) {
-		print STDERR "BUG: ";
-	}
-}
-
-sub chk {
-	my $file = shift;
-	my $line = 0;
-	my $regexp;
-	my @errmsg;
-	my @match;
-	foreach my $src (@{$src{$file}}) {
-		$line++;
-		next if $src =~ m|////|;  # double comment disables ERROR
-		next unless $src =~ m|// (GC_)?ERROR (.*)|;
-		my $all = $2;
-		if($all !~ /^"([^"]*)"/) {
-			print STDERR "$file:$line: malformed regexp\n";
-			next;
-		}
-		@errmsg = grep { /$file:$line[:[]/ } @out;
-		@out = grep { !/$file:$line[:[]/ } @out;
-		if(@errmsg == 0) {
-			bug();
-			print STDERR "errchk: $file:$line: missing expected error: '$all'\n";
-			next;
-		}
-		foreach my $regexp ($all =~ /"([^"]*)"/g) {
-			# Turn relative line number in message into absolute line number.
-			if($regexp =~ /LINE(([+-])([0-9]+))?/) {
-				my $n = $line;
-				if(defined($1)) {
-					if($2 eq "+") {
-						$n += int($3);
-					} else {
-						$n -= int($3);
-					}
-				}
-				$regexp = "$`$file:$n$'";
-			}
-	
-			@match = grep { /$regexp/ } @errmsg;
-			if(@match == 0) {
-				bug();
-				print STDERR "errchk: $file:$line: error messages do not match '$regexp'\n";
-				next;
-			}
-			@errmsg = grep { !/$regexp/ } @errmsg;
-		}
-		if(@errmsg != 0) {
-			bug();
-			print STDERR "errchk: $file:$line: unmatched error messages:\n";
-			foreach my $l (@errmsg) {
-				print STDERR "> $l";
-			}
-		}
-	}
-}
-
-foreach $file (@file) {
-	chk($file)
-}
-
-if(@out != 0) {
-	bug();
-	print STDERR "errchk: unmatched error messages:\n";
-	print STDERR "==================================================\n";
-	print STDERR @out;
-	print STDERR "==================================================\n";
-}
-
-exit 0;