[build] Disable MSCCL++ compilation by default (#1879)

* Enable MSCCLPP on request

* Updating docs and README

* Updates to CHANGELOG.md

* Update CHANGELOG.md

Co-authored-by: Jeffrey Novotny <jnovotny@amd.com>

* Updates to CHANGELOG.md

* Update CHANGELOG.md

Co-authored-by: corey-derochie-amd <161367113+corey-derochie-amd@users.noreply.github.com>

* Update CHANGELOG.md

Github didn't take the edit to my suggestion properly.

---------

Co-authored-by: amd <amd@super3.amd.com>
Co-authored-by: Jeffrey Novotny <jnovotny@amd.com>
Co-authored-by: corey-derochie-amd <161367113+corey-derochie-amd@users.noreply.github.com>

README.md

@@ -43,7 +43,7 @@ RCCL build & installation helper script
        --enable_backtrace      Build with custom backtrace support
        --disable-colltrace     Build without collective trace
        --disable-msccl-kernel  Build without MSCCL kernels
-       --disable-mscclpp       Build without MSCCL++ support
+       --enable-mscclpp        Build with MSCCL++ support
        --enable-mscclpp-clip   Build MSCCL++ with clip wrapper on bfloat16 and half addition routines
        --disable-roctx         Build without ROCTX logging
     -f|--fast                  Quick-build RCCL (local gpu arch only, no backtrace, and collective trace support)