Compilation: Move no_builtin to Package.Module.

This option, by its very nature, needs to be attached to a module. If it isn't,
the code in a module could break at random when compiled into an application
that doesn't have this option set.

After this change, skip_linker_dependencies no longer implies no_builtin in the
LLVM backend.

src/Package/Module.zig

@@ -31,6 +31,7 @@ unwind_tables: bool,
 cc_argv: []const []const u8,
 /// (SPIR-V) whether to generate a structured control flow graph or not
 structured_cfg: bool,
+no_builtin: bool,
 
 /// If the module is an `@import("builtin")` module, this is the `File` that
 /// is preallocated for it. Otherwise this field is null.
@@ -95,6 +96,7 @@ pub const CreateOptions = struct {
         sanitize_thread: ?bool = null,
         fuzz: ?bool = null,
         structured_cfg: ?bool = null,
+        no_builtin: ?bool = null,
     };
 };
 
@@ -298,6 +300,13 @@ pub fn create(arena: Allocator, options: CreateOptions) !*Package.Module {
         };
     };
 
+    const no_builtin = b: {
+        if (options.inherited.no_builtin) |x| break :b x;
+        if (options.parent) |p| break :b p.no_builtin;
+
+        break :b target.cpu.arch.isBpf();
+    };
+
     const llvm_cpu_features: ?[*:0]const u8 = b: {
         if (resolved_target.llvm_cpu_features) |x| break :b x;
         if (!options.global.use_llvm) break :b null;
@@ -350,6 +359,7 @@ pub fn create(arena: Allocator, options: CreateOptions) !*Package.Module {
         .unwind_tables = unwind_tables,
         .cc_argv = options.cc_argv,
         .structured_cfg = structured_cfg,
+        .no_builtin = no_builtin,
         .builtin_file = null,
     };
 
@@ -442,6 +452,7 @@ pub fn create(arena: Allocator, options: CreateOptions) !*Package.Module {
             .unwind_tables = unwind_tables,
             .cc_argv = &.{},
             .structured_cfg = structured_cfg,
+            .no_builtin = no_builtin,
             .builtin_file = new_file,
         };
         new_file.* = .{
@@ -502,6 +513,7 @@ pub fn createLimited(gpa: Allocator, options: LimitedOptions) Allocator.Error!*P
         .unwind_tables = undefined,
         .cc_argv = undefined,
         .structured_cfg = undefined,
+        .no_builtin = undefined,
         .builtin_file = null,
     };
     return mod;