tests: add a missing codesign command in merge_func_ptrauth.swift

rdar://problem/69727772

Author: eeckstein

test/LLVMPasses/merge_func_ptrauth.swift

@@ -2,6 +2,7 @@
 
 // RUN: %empty-directory(%t) 
 // RUN: %target-build-swift -O -module-name=test %s -o %t/a.out
+// RUN: %target-codesign %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s -check-prefix=CHECK-OUTPUT
 
 // REQUIRES: executable_test