Merge "Revert "libprocessgroup: Remove __BEGIN_DECLS and __END_DECLS"" into main am: 5c14720b5a am: 0f0df26b2d

Original change: https://android-review.googlesource.com/c/platform/system/core/+/3366140

Change-Id: I50c90ed016ed1218e74c0d8f24a098909beae46a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>