Disable LTO for cc libraries passed to rustc

Bug: http://b/336916369

Having cross-language LTO adds additional constraints in the LLVM
version used by the rust and clang toolchain.  Disable LTO until
cross-language LTO is supported.

Test: make libring with ToT clang
Change-Id: I30de670db2679f92d34bfb3e391dcafcb13a6d50
1 file changed