Add two tests

com.oracle.truffle.r.test/tests/pgsql/QueryComplex.R

+minsalary = 2500
+emp = new.tableRef("emp", "PostgreSQL", "postgre.config", "public")
+q = query.select(function (x) {
+             res = new.env()
+	     res$empno = x$empno
+             res$ename = x$ename
+             res$salary = (function (dol) dol * 89 / 100)(x$sal)
+             res },
+    query.where(function (x) x$sal >= minsalary,
+    query.from(emp)))
+results = query.force(q)
+print(results)

com.oracle.truffle.r.test/tests/pgsql/QueryComplex.out

+  ename empno  salary
+1 SMITH     1 2225.00
+2  WARD     3 4645.80
+3 JONES     4 3115.00
+4 SCOTT     8 3769.15
+5 ADAMS    11 4450.00
+

com.oracle.truffle.r.test/tests/pgsql/QueryComplex2.R

+minsalary = 2500
+emp = new.tableRef("emp", "PostgreSQL", "postgre.config", "public")
+q = query.select(function (x) {
+             res = new.env()
+	     res$empno = x$empno
+             res$ename = x$ename
+             res$salary = (function (dol) dol * 89 / 100)(x$sal)
+             res },
+    query.where(function (x) x$sal >= minsalary || x$mgr + minsalary > 10300,
+    query.from(emp)))
+results = query.force(q)
+print(results)

com.oracle.truffle.r.test/tests/pgsql/QueryComplex2.out

+   ename empno  salary
+1  SMITH     1 2225.00
+2   WARD     3 4645.80
+3  JONES     4 3115.00
+4  SCOTT     8 3769.15
+5 TURNER    10  975.44
+6  ADAMS    11 4450.00
+7  JAMES    12 1290.50
+8   FORD    13 1682.10
+