Revert "meson: De-dup rpath arguments" #16875

Job	Run time
Arch / PyPy	19m 43s
Ubuntu Rolling (gcc, g++)	19m 58s
Arch Linux	20m 15s
Ubuntu Rolling (--unity=on -Ddefault_library=static, --no-unittests, gcc, g++)	13m 38s
CUDA (on Arch)	7m 19s
Ubuntu Rolling (-Ddefault_library=both, --no-unittests, gcc, g++)	14m 8s
Fedora	20m 18s
Ubuntu Rolling (clang, clang++)	21m 49s
Gentoo	22m 28s
Ubuntu Rolling (--unity=on, --no-unittests, clang, clang++)	15m 40s
OpenSUSE	16m 36s
Ubuntu Rolling (--cross ubuntu-armhf.json --cross linux-mingw-w64-64bit.json, 0, gcc, g++)	13m 50s
Ubuntu Bionic	14m 52s
Ubuntu Rolling (--cross ubuntu-armhf.json --cross linux-mingw-w64-64bit.json, --unity=on, gcc, g++)	13m 52s
	3h 54m 26s

Provide feedback