pppd: Move PLUGIN flag to defaults

Move the PLUGIN flad to cc defaults so that the binary
is compiled with the option enabled.

Original change: https://android-review.googlesource.com/c/platform/external/ppp/+/1706808

Bug: 188035820

Merged-In: Ic727eede2991bf1c8f798c74057be246551479db
Change-Id: Ic727eede2991bf1c8f798c74057be246551479db
diff --git a/pppd/Android.bp b/pppd/Android.bp
index e3138a3..9268d54 100644
--- a/pppd/Android.bp
+++ b/pppd/Android.bp
@@ -60,6 +60,7 @@
         "-Wno-unused-parameter",
         "-Werror",
         "-Wno-pointer-sign",
+        "-DPLUGIN",
     ],
     local_include_dirs: ["include"],
 }
@@ -119,7 +120,6 @@
         "-Wno-empty-body",
         "-Wno-attributes",
         "-Wno-sign-compare",
-        "-DPLUGIN",
     ],
 
     ldflags: ["-rdynamic"],