Fix build on CentOS 6 w/ xmlsec1-1.2.19-3

pkgconfig doesn't parse the XMLSEC_CRYPTO macro value correctly
from xmlsec1-1.2.19-3 on CentOS 6 (the Changelog
for [that RPM](https://centos.pkgs.org/6/centos-x86_64/xmlsec1-1.2.20-4.el6.x86_64.rpm.html)
suggests there's been some bugs).

```
2014-05-28 - Simo Sorce <simo@redhat.com> - 1.2.20-2
- Update pkg-config fix patch to apply w/o fuzz

...

2014-05-23 - Simo Sorce <simo@redhat.com> - 1.2.19-6
- Fix incomplete patch

2014-05-23 - Simo Sorce <simo@redhat.com> - 1.2.19-5
- Add patch to deal with different behavior of pkg-config in RHEL6
```

This change fixes the build for xmlsec1-1.2.19-3.

Author: jtdoepke

xmlsec_setupinfo.py

@@ -174,7 +174,7 @@ def load_xmlsec1_config():
         # fix macros, ensure that macros is list
         macros = list(config.get('define_macros', []))
         for i, v in enumerate(macros):
-            if v[0] == 'XMLSEC_CRYPTO':
+            if v[0] == 'XMLSEC_CRYPTO' and not (v[1].startswith('"') and v[1].endswith('"')):
                 macros[i] = ('XMLSEC_CRYPTO', '"{0}"'.format(v[1]))
                 break
         config['define_macros'] = macros