bp2build: build //system/core/libprocessgroup:libprocessgroup_headers am:...

bp2build: build //system/core/libprocessgroup:libprocessgroup_headers am: 60eaabbe am: c4867e32 am: 2d9dc544 am: eb72be79

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/1814445

Change-Id: I310306bd49783123b506f4f00e8bba662828bb35