imagemagick: try to fix macOS cross building

recipes/imagemagick/all/conanfile.py

@@ -3,6 +3,7 @@
 
 from conan import ConanFile
 from conan.errors import ConanInvalidConfiguration
+from conan.tools.apple import fix_apple_shared_install_name, is_apple_os, XCRun, to_apple_arch
 from conan.tools.build import can_run
 from conan.tools.cmake import CMakeToolchain, CMake
 from conan.tools.env import VirtualRunEnv
@@ -315,6 +316,11 @@ def yes_no(o):
             "--with-djvu={}".format(yes_no(self.options.with_djvu)),
             "--with-utilities={}".format(yes_no(self.options.utilities)),
         ]
+        if self.settings.compiler == "apple-clang":
+            tc.extra_cflags.extend([
+                "-isysroot", XCRun(self).sdk_path,
+                "-arch", to_apple_arch(self),
+            ])
         tc.generate()
 
         deps = AutotoolsDeps(self)