Fix gncInvoice test failure.

test_suite_gncInvoice sets up the test suite. It's not part of the test
runtime, so stack variables in it have gone out of scope by the time the
tests are actually run. Making invoiceData static makes it permanent so
it exists at runtime.

libgnucash/engine/test/utest-Invoice.c

@@ -205,7 +205,7 @@ test_invoice_posted_trans ( Fixture *fixture, gconstpointer pData )
 void
 test_suite_gncInvoice ( void )
 {
-    InvoiceData pData = { FALSE, FALSE, { 1000, 100 }, { 2000, 100 } };  // Vendor bill
+    static InvoiceData pData = { FALSE, FALSE, { 1000, 100 }, { 2000, 100 } };  // Vendor bill
     GNC_TEST_ADD( suitename, "post/unpost", Fixture, &pData, setup, test_invoice_post, teardown );
 
     GNC_TEST_ADD( suitename, "post trans - vendor bill", Fixture, &pData, setup_with_invoice, test_invoice_posted_trans, teardown_with_invoice );