Add X86 backend to clang-apple-cross toolchain

Restore Intel Mac support by building both X86 and AArch64 targets.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: awakecoding

cmake/clang-apple-cross.cmake

@@ -38,8 +38,9 @@ endif()
 
 set(PACKAGE_VENDOR "awakecoding" CACHE STRING "")
 
-# Apple arm64 only: no Intel Mac, no iOS simulator x64, no other backends.
+# Apple x86_64 and arm64: no other backends.
 set(LLVM_TARGETS_TO_BUILD
+    "X86"
     "AArch64"
     CACHE STRING "")