base: remove -latomic in CrOS chroot

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index 7714190534fc23bd8b879ffb3e119916d6c144d3..ccc9647d446f5614bae0b4fc5ed9a6fe5a9c588e 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -1128,8 +1128,11 @@ component("base") {
     ":debugging_flags",
   ]
 
-  # Needed for <atomic> if using newer C++ library than sysroot
-  if (!use_sysroot && (is_android || (is_linux && !is_chromecast))) {
+  # Needed for <atomic> if using newer C++ library than sysroot, except if
+  # building inside the cros_sdk environment - use host_toolchain as a
+  # more robust check for this.
+  if (!use_sysroot && (is_android || (is_linux && !is_chromecast)) &&
+      host_toolchain != "//build/toolchain/cros:host") {
     libs = [ "atomic" ]
   }