CarpetX: Correct interpolation on multiple MPI processes #743

Job	Run time
download-build-test (cpu, real32, debug)	13m 3s
download-build-test (cpu, real64, debug)	15m 12s
download-build-test (cpu, real64, optimize)	25m 4s
download-build-test (cuda, real32, debug)	27m 21s
download-build-test (cuda, real64, debug)	36m 46s
download-build-test (cuda, real64, optimize)	27m 41s
download-build-test (rocm, real64, debug)	21m 0s
download-build-test (rocm, real64, optimize)	21m 27s
	3h 7m 34s

Provide feedback