openmpi: build against external prrte on all platforms

`openmpi` can build against either an external `prrte` or its own
vendored `prrte`.  This change prefers using the external `prrte`
built by Nixpkgs on all platform (including Darwin, now that the
`prrte` build is enabled on all platforms)

pkgs/by-name/op/openmpi/package.nix

@@ -85,6 +85,7 @@ stdenv.mkDerivation (finalAttrs: {
       zlib
       libevent
       hwloc
+      prrte
     ]
     ++ lib.optionals stdenv.hostPlatform.isLinux [
       libnl
@@ -92,7 +93,6 @@ stdenv.mkDerivation (finalAttrs: {
       pmix
       ucx
       ucc
-      prrte
     ]
     ++ lib.optionals cudaSupport [ cudaPackages.cuda_cudart ]
     ++ lib.optionals (stdenv.hostPlatform.isLinux || stdenv.hostPlatform.isFreeBSD) [ rdma-core ]
@@ -119,7 +119,7 @@ stdenv.mkDerivation (finalAttrs: {
     "--with-pmix=${lib.getDev pmix}"
     "--with-pmix-libdir=${lib.getLib pmix}/lib"
     # Puts a "default OMPI_PRTERUN" value to mpirun / mpiexec executables
-    (lib.withFeatureAs stdenv.hostPlatform.isLinux "prrte" (lib.getBin prrte))
+    (lib.withFeatureAs true "prrte" (lib.getBin prrte))
     (lib.withFeature enableSGE "sge")
     (lib.enableFeature enablePrefix "mpirun-prefix-by-default")
     # TODO: add UCX support, which is recommended to use with cuda for the most robust OpenMPI build