linux: Disable compiler TLS in libxml2 (fixes #3616)

patch/patch.cfg

@@ -678,5 +678,10 @@ patches = [
     # https://chromium-review.googlesource.com/c/chromium/src/+/4829483
     # https://bugs.chromium.org/p/chromium/issues/detail?id=1470837#c22
     'name': 'rfh_navigation_4829483'
+  },
+  {
+    # linux: Disable compiler TLS in libxml2.
+    # https://github.com/chromiumembedded/cef/issues/3616
+    'name': 'linux_libxml_tls_3616'
   }
 ]

patch/patches/linux_libxml_tls_3616.patch

@@ -0,0 +1,13 @@
+diff --git third_party/libxml/linux/config.h third_party/libxml/linux/config.h
+index c064071ce1545..65110af9a78f5 100644
+--- third_party/libxml/linux/config.h
++++ third_party/libxml/linux/config.h
+@@ -171,7 +171,7 @@
+ /* #undef XML_SOCKLEN_T */
+ 
+ /* TLS specifier */
+-#define XML_THREAD_LOCAL _Thread_local
++/* #undef XML_THREAD_LOCAL */
+ 
+ /* Define for Solaris 2.5.1 so the uint32_t typedef from <sys/synch.h>,
+    <pthread.h>, or <semaphore.h> is not used. If the typedef were allowed, the