Redefine is_linux to not include Android in the GN build.

tools/gn/secondary/third_party/libxml/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Define an "os_include" variable that points at the OS-specific generated
 # headers.  These were generated by running the configure script offline.
-if (is_linux) {
+if (is_linux || is_android) {
   os_include = "linux"
 } else if (is_mac || is_ios) {
   os_include = "mac"
 } else if (is_win) {
   os_include = "win32"
 }
 
 config("libxml_config") {
   # Define LIBXML_STATIC as nothing to match how libxml.h (an internal header)
   # defines LIBXML_STATIC, otherwise we get the macro redefined warning from
@@ skipping 130 matching lines @@
 
   deps = [
     "//third_party/icu:icuuc",
     "//third_party/zlib",
   ]
 
   if (is_win) {
     cflags_c = [
       "/wd4101",  # Unreferenced local variable.
     ]
-  } else if (is_linux) {
-    # We need dl for dlopen() and friends.
-    libs = [ "dl" ]
   } else if (is_mac || is_android) {
     # http://www.xmlsoft.org/threads.html says that this is required when using
     # libxml from several threads, which can possibly happen in chrome. On
     # linux, this is picked up by transitivity from pkg-config output from
     # build/linux/system.gyp.
     defines = [ "_REENTRANT" ]
   }
 
   if (is_clang) {
     cflags = [
       # libxml passes `const unsigned char*` through `const char*`.
       "-Wno-pointer-sign",
 
       # pattern.c and uri.c both have an intentional `for (...);` /
       # `while(...);` loop. I submitted a patch to move the `'` to its own
       # line, but until that's landed suppress the warning:
       "-Wno-empty-body",
 
       # See http://crbug.com/138571#c8
       "-Wno-ignored-attributes",
     ]
   }
 
   include_dirs = [
     "$os_include",
   ]
 }