[Fuchsia] Disable PIC (llvm#136376)

We aren't distributing any shared libraries so we don't need PIC and
using PIE instead of PIC can improve performance.

Author: petrhosek

clang/cmake/caches/Fuchsia-stage2.cmake

@@ -18,6 +18,7 @@ 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_UNWIND_TABLES OFF CACHE BOOL "")
 set(LLVM_ENABLE_Z3_SOLVER OFF CACHE BOOL "")