Disable -Wcast-function-type-mismatch

Code owners should fix this.
```
.../obj/bionic/tests/stdio_ext_test.o.d -o out/soong/.intermediates/bionic/tests/libBionicStandardTests/android_x86_silvermont_static_cov/obj/bionic/tests/stdio_ext_test.o bionic/tests/stdio_ext_test.cpp
...test.cpp:251:31: error: cast from 'void (*)(std::atomic<pid_t> *)' (aka 'void (*)(atomic<int> *)') to 'void *(*)(void *)' converts to incompatible function type [-Werror,-Wcast-function-type-mismatch]
  251 |                               reinterpret_cast<void* (*)(void*)>(LockingByCallerHelper), &pid));
      |                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```

Bug: b/353528991
Change-Id: I9b34705e220dc62ffe913c5942cb5ee8e43dd20e
Test: m checkbuild
diff --git a/tests/pty_test.cpp b/tests/pty_test.cpp
index d5d8994..6e3d2c7 100644
--- a/tests/pty_test.cpp
+++ b/tests/pty_test.cpp
@@ -103,6 +103,8 @@
   arg->finished = true;
 }
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wcast-function-type-mismatch"
 TEST(pty, bug_28979140) {
   // This test is to test a kernel bug, which uses a lock free ring-buffer to
   // pass data through a raw pty, but missing necessary memory barriers.
@@ -164,3 +166,4 @@
   ASSERT_TRUE(arg.matched);
   close(pty);
 }
+#pragma clang diagnostic pop
\ No newline at end of file