[CMake] Drop libLTO and switch to PIE for Fuchsia toolchain

[phosek]

Summary

All our users have migrated to ld64.lld so we no longer need libLTO.

[abrachet]

Nice thats 71mb saved :)

clang/cmake/caches/Fuchsia-stage2.cmake

 # This file sets up a CMakeCache for the second stage of a Fuchsia toolchain build.
 
 set(LLVM_TARGETS_TO_BUILD X86;ARM;AArch64;RISCV CACHE STRING "")
 
 set(PACKAGE_VENDOR Fuchsia CACHE STRING "")
 
 set(LLVM_ENABLE_PROJECTS "bolt;clang;clang-tools-extra;lld;llvm;polly" CACHE STRING "")
 set(LLVM_ENABLE_RUNTIMES "compiler-rt;libcxx;libcxxabi;libunwind" CACHE STRING "")
 
 set(LLVM_ENABLE_BACKTRACES OFF CACHE BOOL "")
 set(LLVM_ENABLE_DIA_SDK OFF CACHE BOOL "")
 set(LLVM_ENABLE_LIBCXX ON CACHE BOOL "")
 set(LLVM_ENABLE_LIBEDIT OFF CACHE BOOL "")
 set(LLVM_ENABLE_LLD ON CACHE BOOL "")
 set(LLVM_ENABLE_LTO ON CACHE BOOL "")
 set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR ON CACHE BOOL "")
+set(LLVM_ENABLE_PIC OFF CACHE BOOL "")
 set(LLVM_ENABLE_PLUGINS OFF CACHE BOOL "")
 set(LLVM_ENABLE_TERMINFO OFF CACHE BOOL "")
 set(LLVM_ENABLE_UNWIND_TABLES OFF CACHE BOOL "")
 set(LLVM_ENABLE_Z3_SOLVER OFF CACHE BOOL "")
 set(LLVM_ENABLE_ZLIB ON CACHE BOOL "")
 set(LLVM_INCLUDE_DOCS OFF CACHE BOOL "")
 set(LLVM_INCLUDE_EXAMPLES OFF CACHE BOOL "")
 set(LLVM_INCLUDE_GO_TESTS OFF CACHE BOOL "")
set(LLVM_TOOLCHAIN_TOOLS
   llvm-xray
   sancov
   scan-build-py
   CACHE STRING "")
 
 set(LLVM_DISTRIBUTION_COMPONENTS
   clang
   lld
-  LTO
   clang-apply-replacements
   clang-doc
   clang-format
   clang-resource-headers
   clang-include-fixer
   clang-refactor
   clang-scan-deps
   clang-tidy
   clangd
   find-all-symbols
   builtins
   runtimes
   ${LLVM_TOOLCHAIN_TOOLS}
   CACHE STRING "")