[UR] Allow compilation on apple for OpenCL support #1790

Job	Run time
Build - Windows (windows-2019, Debug)	10m 56s
Build - Windows (windows-2019, Release)	13m 10s
Build - Windows (windows-2022, Debug)	14m 32s
Build - Windows (windows-2022, Release)	14m 58s
Build - Ubuntu (ubuntu-20.04, Debug, gcc, g++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=OFF)	13m 31s
Build - Ubuntu (ubuntu-20.04, Release, gcc, g++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=OFF)	11m 30s
Build - Ubuntu (ubuntu-22.04, Debug, gcc, g++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=OFF)	9m 49s
Build - Ubuntu (ubuntu-22.04, Release, gcc, g++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=OFF)	12m 2s
Build - Ubuntu (ubuntu-22.04, Release, clang, clang++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=OFF)	11m 11s
Build - Ubuntu (ubuntu-22.04, Release, gcc, g++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=ON)	14m 30s
Build - Ubuntu (ubuntu-22.04, Release, clang, clang++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=ON)	15m 39s
Build - Ubuntu (ubuntu-20.04, Release, gcc-7, g++-7)	10m 19s
Build - MacOS (macos-12)	7m 14s
Build - MacOS (macos-13)	4m 47s
	2h 44m 8s

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