CXX_EXTRA_FLAGS does not support passing multiple flags #4
Description
Building fails when CXX_EXTRA_FLAGS contains more than one flag:
cmake -Btest -H. -DCMAKE_BUILD_TYPE=Release -DSYCL_RUNTIME=HIPSYCL -DCXX_EXTRA_FLAGS='-march=armv8.3-a+sve -ffp-contract=fast'
cmake --build test --target clover_leaf --config Release -j 1 -v
The flags aren't properly passed to the compiler (full paths removed for clarity):
...
[ 3%] Building SYCL object CMakeFiles/clover_leaf.dir/src/accelerate.cpp.o
syclcc-clang -I... -W... -O3 "-march=armv8.3-a+sve -ffp-contract=fast" -pthread -o ...
cc1plus: error: invalid feature modifier in ‘-march=armv8.3-a+sve -ffp-contract=fast’
Setting a single flag, e.g. -DCXX_EXTRA_FLAGS=-march=armv8.3-a+sve, works correctly.