maint: ignore new test executable

* tests/.gitignore: Sort, and add sockettest.

tests/.gitignore

-Makefile
-Makefile.in
+*.exe
 .deps
 .libs
-sexpr2xmltest
-xml2sexprtest
-virshtest
 conftest
-reconnect
-xmconfigtest
-xencapstest
-qemuxml2xmltest
-qemuxml2argvtest
-qemuargv2xmltest
-qemuhelptest
+esxutilstest
+eventtest
+interfacexml2xmltest
 networkxml2xmltest
 nodedevxml2xmltest
-interfacexml2xmltest
-storagevolxml2xmltest
-storagepoolxml2xmltest
 nodeinfotest
-statstest
-qparamtest
-virbuftest
-seclabeltest
-eventtest
-*.exe
 object-locking
+object-locking-files.txt
 object-locking.cmi
 object-locking.cmx
-object-locking-files.txt
-esxutilstest
+qemuargv2xmltest
+qemuhelptest
+qemuxml2argvtest
+qemuxml2xmltest
+qparamtest
+reconnect
+secaatest
+seclabeltest
+sexpr2xmltest
+sockettest
+statstest
+storagepoolxml2xmltest
+storagevolxml2xmltest
+virbuftest
+virshtest
 vmx2xmltest
+xencapstest
+xmconfigtest
+xml2sexprtest
 xml2vmxtest
-secaatest