Only check arch tag if we have *any* arch tags.

With the introduction of new tags for ndk_library, we'll have a lot
of tags that aren't architecture tags. If we have something tagged
`introduced=21`, it should be in all architectures.

Change-Id: Ib67f07db14625f6903919c181050316eb183bed5
diff --git a/libc/tools/genversion-scripts.py b/libc/tools/genversion-scripts.py
index e6c8053..53f4db4 100755
--- a/libc/tools/genversion-scripts.py
+++ b/libc/tools/genversion-scripts.py
@@ -33,6 +33,15 @@
 warning = "Generated by %s. Do not edit." % script_name
 
 
+def has_arch_tags(tags):
+  for arch in all_arches:
+    if arch in tags:
+      return True
+  if 'nobrillo' in tags:
+    return True
+  return False
+
+
 class VersionScriptGenerator(object):
 
   def run(self):
@@ -52,7 +61,7 @@
                 index = line.find("#")
                 if index != -1:
                   tags = line[index+1:].split()
-                  if arch not in tags:
+                  if arch not in tags and has_arch_tags(tags):
                     continue
                   if brillo and "nobrillo" in tags:
                     has_nobrillo = True