[libc] include sdk path

Signed-off-by: Shreeyash Pandey <[email protected]>

Author: bojle

libc/cmake/modules/LLVMLibCCompileOptionRules.cmake

@@ -170,6 +170,19 @@ function(_get_common_compile_options output_var flags)
           list(APPEND compile_options "-idirafter${LIBC_KERNEL_HEADERS}")
         endif()
       endif()
+      if(LIBC_TARGET_OS_IS_DARWIN)
+        execute_process(
+          COMMAND xcrun --sdk macosx --show-sdk-path
+          OUTPUT_VARIABLE MACOSX_SDK_PATH
+          RESULT_VARIABLE MACOSX_SDK_PATH_RESULT
+          OUTPUT_STRIP_TRAILING_WHITESPACE
+        )
+        if(MACOSX_SDK_PATH_RESULT EQUAL 0)
+          list(APPEND compile_options "-I" "${MACOSX_SDK_PATH}/usr/include")
+        else()
+          message(WARNING "Could not find macOS SDK path. `xcrun --sdk macosx --show-sdk-path` failed.")
+        endif()
+      endif()
     endif()
 
     if(LIBC_COMPILER_HAS_FIXED_POINT)