Use NO_IMEMORY version of libstagefright_foundation for apex

Currently swcodec apex build uses vendor variant which no longer
depends on libbinder. However, in some builds VNDK is not used
and libbinder dependency still exists. Although the prebuilt
apex no longer contains libbinder, some build still fails when
libbinder is disallowed in apex.

Create a separate version of libstagefright_foundataion_no_imemory,
and use that only if there is no vendor build.

Also do not use __ANDROID_VNDK__ to disable the binder related
code in libstagefright_foundation, it's never defined if there is
no VNDK. Use NO_IMEMORY instead.

bug: 139201422
bug: 139016109

test: various builds in presubmit
Change-Id: I045836e10b93f71c7c31b30bb555eea8d6a2ef3a