AutoDiff: repair the test on Windows

The name of the module is encoded into the type name.  The module name
is not `null` on Windows, which would fail to match the name.  It is
possible to make the test less overly-constricted, but setting the
module name to null is simpler and avoids more regex matching.

Author: compnerd

test/AutoDiff/validation-test/simple_math.swift

@@ -1,7 +1,7 @@
 // RUN: %target-run-simple-swift
 // NOTE(TF-813): verify that enabling forward-mode does not affect reverse-mode.
 // RUN: %target-run-simple-swift(-Xfrontend -enable-experimental-forward-mode-differentiation)
-// RUN: %target-swift-frontend -Xllvm -sil-print-after=differentiation %s -emit-sil -o /dev/null 2>&1 | %FileCheck %s
+// RUN: %target-swift-frontend -Xllvm -sil-print-after=differentiation %s -emit-sil -o /dev/null -module-name null 2>&1 | %FileCheck %s
 // REQUIRES: executable_test
 
 import StdlibUnittest
@@ -367,7 +367,7 @@ SimpleMathTests.test("ForceUnwrapping") {
 }
 
 // CHECK-LABEL: sil private [ossa] @AD__${{.*}}jumpTimesTwo{{.*}}pullback_src_0_wrt_0 : $@convention(thin) (Float, @owned _AD__$s4nullyycfU18_12jumpTimesTwoL_5modelSfAAyycfU18_14SmallTestModelL_V_tF_bb0__PB__src_0_wrt_0) -> SmallTestModel.TangentVector {
-// CHECK: bb0([[DX:%.*]] : $Float,  [[PB_STRUCT:%.*]] : {{.*}}):
+// CHECK: bb0([[DX:%.*]] : $Float, [[PB_STRUCT:%.*]] : {{.*}}):
 // CHECK:   ([[PB0:%.*]], [[PB1:%.*]]) = destructure_struct [[PB_STRUCT]]
 // CHECK:   [[ADJ_TUPLE:%.*]] = apply [[PB1]]([[DX]]) : $@callee_guaranteed (Float) -> (Float, Float)
 // CHECK:   ([[TMP0:%.*]], [[ADJ_CONCRETE:%.*]]) = destructure_tuple [[ADJ_TUPLE]] : $(Float, Float)