Revert removing of compile_assert.h.
Revert removing of compile_assert.h.

In https://webrtc-codereview.appspot.com/39469004 compile_assert.h is removed and that resulted in some bots to break. There is a pending CL to fix the issue https://chromereviews.googleplex.com/141837013/
, meanwhile I revert this change.

TBR=kwiberg@google.com

Review URL: https://webrtc-codereview.appspot.com/35779004

git-svn-id: 03ae4fbe531b1eefc9d815f31e49022782c42458@8064 4adac7df-926f-26a2-2b94-8c16560cd09d

Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,jchavanton/webrtc,aleonliao/webrtc-trunk,Alkalyne/webrtctrunk,jchavanton/webrtc,krieger-od/webrtc,aleonliao/webrtc-trunk,sippet/webrtc,aleonliao/webrtc-trunk,sippet/webrtc,aleonliao/webrtc-trunk,Alkalyne/webrtctrunk,krieger-od/webrtc,aleonliao/webrtc-trunk,sippet/webrtc,Alkalyne/webrtctrunk,jchavanton/webrtc,krieger-od/webrtc,krieger-od/webrtc,aleonliao/webrtc-trunk,Alkalyne/webrtctrunk,sippet/webrtc,jchavanton/webrtc,Alkalyne/webrtctrunk,krieger-od/webrtc,sippet/webrtc,sippet/webrtc,Alkalyne/webrtctrunk,jchavanton/webrtc,jchavanton/webrtc,jchavanton/webrtc,krieger-od/webrtc