std.fs.Dir: no flock when not defined

Author: RossComputerGuy

lib/std/debug/SelfInfo.zig

@@ -146,6 +146,8 @@ pub fn getModuleNameForAddress(self: *SelfInfo, address: usize) ?[]const u8 {
         return self.lookupModuleNameWin32(address);
     } else if (native_os == .haiku) {
         return null;
+    } else if (native_os == .uefi) {
+        return null;
     } else if (builtin.target.isWasm()) {
         return null;
     } else {

lib/std/fs/Dir.zig

@@ -2787,4 +2787,4 @@ const assert = std.debug.assert;
 const linux = std.os.linux;
 const windows = std.os.windows;
 const native_os = builtin.os.tag;
-const have_flock = @TypeOf(posix.system.flock) != void;
+const have_flock = @hasDecl(posix.system, "flock") and @TypeOf(posix.system.flock) != void;