iox-#XXXX Auto-detect sys/acl.h availability on Linux

On Linux, IOX_PLATFORM_FEATURE_ACL previously defaulted to ON
unconditionally. This causes build failures when using hermetic
toolchains (e.g. Zig/clang sysroots) that do not provide sys/acl.h
or libacl.

Use CMake's check_include_file to probe for sys/acl.h at configure
time. If the header is absent, default IOX_PLATFORM_FEATURE_ACL to
OFF so the existing no-op stub is used instead. The option can still
be overridden explicitly by the user.

This unblocks hermetic and minimal toolchain builds without requiring
out-of-tree patches (e.g. rules_ros2_iceoryx_no_acl.patch).

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Author: guominx

iceoryx_platform/linux/cmake/IceoryxPlatformDeployment.cmake

@@ -38,7 +38,16 @@ configure_option(
     DEFAULT_VALUE "/etc/"
 )
 
-option(IOX_PLATFORM_FEATURE_ACL "Use ACLs for access control" ON)
+include(CheckIncludeFile)
+check_include_file("sys/acl.h" IOX_HAVE_SYS_ACL_H)
+if(IOX_HAVE_SYS_ACL_H)
+    set(IOX_PLATFORM_FEATURE_ACL_DEFAULT ON)
+else()
+    message(STATUS "[i] sys/acl.h not found - disabling ACL support (hermetic or minimal toolchain detected)")
+    set(IOX_PLATFORM_FEATURE_ACL_DEFAULT OFF)
+endif()
+
+option(IOX_PLATFORM_FEATURE_ACL "Use ACLs for access control" ${IOX_PLATFORM_FEATURE_ACL_DEFAULT})
 message(STATUS "[i] IOX_PLATFORM_FEATURE_ACL: ${IOX_PLATFORM_FEATURE_ACL}")
 
 message(STATUS "[i] <<<<<<<<<<<<<< End iceoryx_platform configuration: >>>>>>>>>>>>>>")