Revert "Add rcGetHostExtensions()"

Revert "Add rcGetHostExtensions()"

Revert submission 2216672-gfxstream-rcgethostextensionsstring

Reason for revert: breaks emulator appcompat b/246959520
Reverted Changes:
I4a40ca645:Use rcGetHostExtensions() in HostConnection
I864c29707:Add rcGetHostExtensions()

Change-Id: I3573f9c3ba0591ee0183e1bcb2a86c1195cea485
7 files changed