ANDROID: Improve module loader checks for GKI symbol protection

* Deny loading of unsigned modules which use protected vmlinux
  symbols.
* Optimize symbols resolution for unsigned modules by avoiding
  searching for symbols exported by other unsigned modules in the list
  of unprotected symbols.

Bug: 343540599
Change-Id: I64bc03ad9e37ec7e85be2099d0132966ffe1b35b
Signed-off-by: Sid Nayyar <sidnayyar@google.com>
(cherry picked from commit 8faec9dd)