Fix build failure caused by erroneous use of an undeclared symbol.

Patch copied from upstream bug report:
https://rt.cpan.org/Public/Bug/Display.html?id=117793

From 0be0223422e6e5f4091c6e4e058d213623eed105 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= <ppisar@redhat.com>
Date: Mon, 12 Sep 2016 14:40:44 +0200
Subject: [PATCH] Skip preprocessor symbol only CURL_STRICTER
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CURL_STRICTER leaked into curl-constants.c when building against
curl-7.50.2. This is a preprocessor only macro without a value.

CPAN RT#117793

Signed-off-by: Petr Písař <ppisar@redhat.com>
---
 Makefile.PL | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile.PL b/Makefile.PL
index f9170bb..ad2bd3d 100644
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -127,7 +127,7 @@ if (!defined($curl_h)) {
     close H;
 
     for my $e (sort @syms) {
-       if($e =~ /(OBSOLETE|^CURL_EXTERN|_LAST\z|_LASTENTRY\z)/) {
+       if($e =~ /(OBSOLETE|^CURL_EXTERN|^CURL_STRICTER\z|_LAST\z|_LASTENTRY\z)/) {
           next;
        }
        my ($group) = $e =~ m/^([^_]+_)/;
-- 
2.7.4