Use base's dllmain.cc
Use base's dllmain.cc

This is needed to link successfully (we need a DllMain function), and
matches what chrome.dll does.

electron/libchromiumcontent,brave/libchromiumcontent,hokein/libchromiumcontent,eric-seekas/libchromiumcontent,paulcbetts/libchromiumcontent,deepak1556/libchromiumcontent,jlord/libchromiumcontent,electron/libchromiumcontent,brave/libchromiumcontent,bbondy/libchromiumcontent,bbondy/libchromiumcontent,jlord/libchromiumcontent,zhanggyb/libchromiumcontent,atom/libchromiumcontent,paulcbetts/libchromiumcontent,adamjgray/libchromiumcontent,adamjgray/libchromiumcontent,deepak1556/libchromiumcontent,synaptek/libchromiumcontent,atom/libchromiumcontent,zhanggyb/libchromiumcontent,hokein/libchromiumcontent,synaptek/libchromiumcontent,eric-seekas/libchromiumcontent