Revert "Allow dynamic linking for iOS/tvOS targets."

This reverts commit 56e115a.

Author: francesca64

compiler/rustc_target/src/spec/apple_sdk_base.rs

@@ -34,6 +34,7 @@ fn link_env_remove(arch: Arch) -> Vec<String> {
 pub fn opts(arch: Arch) -> TargetOptions {
     TargetOptions {
         cpu: target_cpu(arch),
+        dynamic_linking: false,
         executables: true,
         link_env_remove: link_env_remove(arch),
         has_elf_tls: false,