sosy-lab#357: replace check for boolean constants with direct pointer…

… comparison.

Z3 uses internal formula hashing,
thus there should not be multiple pointers to the same boolean constants.

This reduces the number of JNI calls for some simple cases.

src/org/sosy_lab/java_smt/solvers/z3/Z3BooleanFormulaManager.java

@@ -152,12 +152,12 @@ protected Long implication(Long pBits1, Long pBits2) {
 
   @Override
   protected boolean isTrue(Long pParam) {
-    return isOP(z3context, pParam, Z3_decl_kind.Z3_OP_TRUE);
+    return z3true.equals(pParam);
   }
 
   @Override
   protected boolean isFalse(Long pParam) {
-    return isOP(z3context, pParam, Z3_decl_kind.Z3_OP_FALSE);
+    return z3false.equals(pParam);
   }
 
   @Override