Fix memory leak of Subzero global inits.

Fix memory leak of Subzero global inits.

getGlobalInits() moves ownership of a unique_ptr<>, which we released
to obtain the raw pointer, but we didn't delete it afterwards. This is
fixed by keeping the unique_ptr<> and having it freed at the end of the
scope.

Bug chromium:732739

Change-Id: I4d8c9367f34790944daabc0417af08eb4b4c7c2e
Reviewed-on: https://swiftshader-review.googlesource.com/10409
Tested-by: Nicolas Capens <capn@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>