Rewrite calls to bitcast unprototyped functions when emitting a definition.

My variadics patch, r169588, changed these calls to typically be
bitcasts rather than calls to a supposedly variadic function.
This totally subverted a hack where we intentionally dropped
excess arguments from such calls in order to appease the inliner
and a "warning" from the optimizer.  This patch extends the hack
to also work with bitcasts, as well as teaching it to rewrite
invokes.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@170034 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/exceptions.c b/test/CodeGen/exceptions.c
index 20eb706..311bc84 100644
--- a/test/CodeGen/exceptions.c
+++ b/test/CodeGen/exceptions.c
@@ -19,3 +19,12 @@
   // CHECK-ARM:      landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__gcc_personality_sj0 to i8*)
   // CHECK-ARM-NEXT:   cleanup
 }
+
+void test2_helper();
+void test2() {
+  __block int x = 10;
+  test2_helper(5, 6, 7);
+}
+void test2_helper(int x, int y) {
+}
+// CHECK: invoke void @test2_helper(i32 5, i32 6)