[Test] Complicate a "fast" type checker test to make it slow.

This test only happened to be under the constraint system thresholds,
but the performance was not fast. Add a few operands to the + chain,
and disable shrink to push the solver past the performance thresholds.

Author: hborla

validation-test/Sema/type_checker_perf/fast/rdar26564101.swift renamed to validation-test/Sema/type_checker_perf/slow/rdar26564101.swift

@@ -1,8 +1,10 @@
-// RUN: %target-typecheck-verify-swift -solver-expression-time-threshold=1
+// RUN: %target-typecheck-verify-swift -solver-expression-time-threshold=1 -solver-disable-shrink
 // REQUIRES: tools-release,no_asan
 // UNSUPPORTED: swift_test_mode_optimize_none && OS=linux-gnu
 
 func rdar26564101(a: [Double], m: Double) -> Double {
-  return Double(Array(0...a.count - 1).reduce(0) { $0 + $1 - m })
-  // expected-error@-1 {{cannot convert value of type}}
+  // expected-error@+1 {{unable to type-check this expression in reasonable time}}
+  return Double(Array(0...a.count - 1).reduce(0) {
+    $0 + $1 - m + $0 + $1 + $0
+  })
 }