Add ndk_headers module for unified headers.

Test: make checkbuild
Bug: http://b/30465923
Change-Id: I5a3ddc895f5c8dc925c5406d9ccdb021770b8b30
diff --git a/Android.bp b/Android.bp
index f54aa67..9ae9398 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1611,4 +1611,4 @@
     sdk_version: "24",
 }
 
-build = ["stl.bp"]
+build = ["bionic.bp", "stl.bp"]
diff --git a/bionic.bp b/bionic.bp
new file mode 100644
index 0000000..04ec37a
--- /dev/null
+++ b/bionic.bp
@@ -0,0 +1,7 @@
+// Update with bionic/tools/update_headers.sh.
+ndk_headers {
+    name: "libc_unified_headers",
+    from: "headers",
+    to: "",
+    srcs: ["headers/**/*.h"],
+}
diff --git a/gen-blueprints.py b/gen-blueprints.py
index d9276ec..18afd47 100755
--- a/gen-blueprints.py
+++ b/gen-blueprints.py
@@ -136,7 +136,7 @@
         f.write('\n')
         f.write('\n\n'.join(blueprints))
         f.write('\n\n')
-        f.write('build = ["stl.bp"]\n')
+        f.write('build = ["bionic.bp", "stl.bp"]\n')
 
 
 if __name__ == '__main__':