linker: Remove setting _USING_LIBCXX
As of aosp/1086558, stdatomic.h directly checks for the presence of
<atomic> instead of checking _USING_LIBCXX, so these lines are
obsolete.
Test: build
Change-Id: Icfdb47b3ad109421b3413041f3d3027e2c0b518e
diff --git a/linker/Android.bp b/linker/Android.bp
index 5e7a921..bdb7c17 100644
--- a/linker/Android.bp
+++ b/linker/Android.bp
@@ -177,11 +177,6 @@
"-Wextra",
"-Wunused",
"-Werror",
-
- // Define _USING_LIBCXX so <stdatomic.h> defers to the <atomic> header. When a Soong module
- // uses the platform libc++, Soong automatically passes this macro, but the dynamic linker
- // links against libc++ manually.
- "-D_USING_LIBCXX",
],
// TODO: split out the asflags.