Populate SDK with clang linker (lld) in addition to GNU linker.

Note that clang linker is multi-target whereas GNU linker is
single-target; so while we need multiple GNU linkers (because we
support multiple targets) we only need a single clang linker.

We retain the GNU linkers so that a new SDK is still compatible with
older gradle plugins.

Bug: 142590626
Bug: 144040336

Test: (gLinux) m PRODUCT-sdk_phone_armv7-sdk dist sdk_repo
      (gLinux) m PRODUCT-sdk_phone_armv7-win_sdk dist sdk_repo

Change-Id: I2a04f6fd464b5eb6a2e9a632f49409c1d7e60170
(cherry picked from commit c22ed0eeceeed54d5f119f66aa3098c2b59c1566)
3 files changed