java/openjdk16: fix build with clang 12

During an exp-run for llvm 12 (see bug 255570), it turned out that at
least openjdk11 and openjdk12 do not build with clang 12.0.0. The
exp-run therefore skipped openjdk16.

Building this manually shows that it results in a compile error:

gmake[4]: Leaving directory '/wrkdirs/usr/ports/java/openjdk16/work/jdk16u-jdk-16.0.1-9-1/make'
/wrkdirs/usr/ports/java/openjdk16/work/jdk16u-jdk-16.0.1-9-1/src/hotspot/cpu/x86/vm_version_ext_x86.cpp:748:3: error: suspicious concatenation of string literals in an array initialization; did you mean to separate the elements with a comma? [-Werror,-Wstring-concatenation]
  "",
  ^
/wrkdirs/usr/ports/java/openjdk16/work/jdk16u-jdk-16.0.1-9-1/src/hotspot/cpu/x86/vm_version_ext_x86.cpp:747:3: note: place parentheses around the string literal to silence warning
  "Opteron QC/Phenom"  // Barcelona et.al.
  ^
1 error generated.

This is due to a missing backport of this upstream commit:

commit f8a9602a0a65cdc98eb940aac9529256ded2bf42
Author: Yasumasa Suenaga <ysuenaga@openjdk.org>
Date:   Thu Jan 21 06:08:13 2021 +0000

    8260025: Missing comma in VM_Version_Ext::_family_id_amd

    Reviewed-by: dholmes, stuefe

Approved by:	maintainer timeout (2 weeks)
PR:		255905
MFH:		2021Q2

java/openjdk16/files/patch-commit-f8a9602a0a6

@@ -0,0 +1,28 @@
+commit f8a9602a0a65cdc98eb940aac9529256ded2bf42
+Author: Yasumasa Suenaga <ysuenaga@openjdk.org>
+Date:   Thu Jan 21 06:08:13 2021 +0000
+
+    8260025: Missing comma in VM_Version_Ext::_family_id_amd
+
+    Reviewed-by: dholmes, stuefe
+
+diff --git src/hotspot/cpu/x86/vm_version_ext_x86.cpp src/hotspot/cpu/x86/vm_version_ext_x86.cpp
+index 30d9494c654..a84b37f7977 100644
+--- src/hotspot/cpu/x86/vm_version_ext_x86.cpp
++++ src/hotspot/cpu/x86/vm_version_ext_x86.cpp
+@@ -1,5 +1,5 @@
+ /*
+- * Copyright (c) 2013, 2019, Oracle and/or its affiliates. All rights reserved.
++ * Copyright (c) 2013, 2021, Oracle and/or its affiliates. All rights reserved.
+  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+  *
+  * This code is free software; you can redistribute it and/or modify it
+@@ -739,7 +739,7 @@ const char* const VM_Version_Ext::_family_id_amd[ExtendedFamilyIdLength_AMD] = {
+   "",
+   "",
+   "Opteron/Athlon64",
+-  "Opteron QC/Phenom"  // Barcelona et.al.
++  "Opteron QC/Phenom",  // Barcelona et.al.
+   "",
+   "",
+   "",