DuneMPI: append flags to `COMPILE_OPTIONS` instead of `COMPILE_FLAGS`
COMPILE_FLAGS
is a string, but set_property(... APPEND ...)
appends to a list. If the list of compile flags is not empty this
results in a superfluous semicolon in the compile flags which will
break the compiler invocation.
For example, when MPI_DUNE_COMPILE_FLAGS=-lpthread
, calling
add_dune_mpi_flags
twice for the same target would result in the
compiler command containing -lpthread;-lpthread
.
This patch makes use of the COMPILE_OPTIONS
property instead which
is a list.