JBMC: Fix failing regression test

A recent modification to https://github.com/diffblue/java-models-library has
made the CProver class to lose its class initializer, which resulted in a
failing regression test here.

Author: cesaro

jbmc/regression/jbmc/coreModels/test.desc

@@ -3,7 +3,12 @@ test.class
 --show-symbol-table --cp ../../../src/java_bytecode/library/core-models.jar:.
 ^EXIT=0$
 ^SIGNAL=0$
-^Symbol\s*\.*\: java\:\:org\.cprover\.CProver\.\<clinit\>\:\(\)V$
+^Symbol.*: java::org.cprover.CProver.assume:\(
+^Symbol.*: java::org.cprover.CProver.nondetInt:\(
+^Symbol.*: java::org.cprover.CProver.nondetChar:\(
 --
+^failed to load class .org.cprover.CProver.$
 --
-tests that the core models are  being loaded by checking if the static initializer for the CProver class was
+This checks that the core models are being loaded. We check that methods
+assume(), nodetInt(), and nondetChar() are defined in class org.cprover.CProver
+and that JBMC does not complain while trying to load the that class.