Revert "libprocessgroup: Remove __BEGIN_DECLS and __END_DECLS"

This reverts commit fdf4432356ddb597f46cfb7b047ab4e0bb808ba2.

Reason for revert: b/379796721

Change-Id: I34cdc69d5b8d11446da02106b7bd593a8c8151c3
1 file changed