Linux: allow linking directly with Kerberos instead of using dlopen.

net/net.gyp

Index: net/net.gyp
diff --git a/net/net.gyp b/net/net.gyp
index fb55d21a90265a66082c40b784df50cc1c00ab53..8f43b69a656b9e458746bf7b755849a1421d97c3 100644
--- a/net/net.gyp
+++ b/net/net.gyp
@@ -7,6 +7,7 @@
     'chromium_code': 1,
 
     'use_kerberos%': 1,
+    'linux_link_kerberos%': 0,
   },
   'targets': [
     {
@@ -710,6 +711,19 @@
           'defines': [
             'USE_KERBEROS',
           ],
+          'conditions': [
+            ['linux_link_kerberos==1', {
+              'link_settings': {
+                'ldflags': [
+                  '<!@(krb5-config --libs gssapi)',
+                ],
+              },
+            }, { # linux_link_kerberos==0
+              'defines': [
+                'DLOPEN_KERBEROS',
+              ],
+            }],
+          ],
         }, { # use_kerberos == 0
           'sources!': [
             'http/http_auth_gssapi_posix.cc',