[OpenMP] libomp: Fix handling of barrier pattern environment variables

It is better to set all barrier patterns to use "dist" when at least
one environment variable specifies "dist". Otherwise if only one
environment is set to "dist" and others left blank inadvertently,
it would result in mixing dist barrier with default hyper barrier
pattern.

Differential Revision: https://reviews.llvm.org/D112597

GitOrigin-RevId: 0808d956c43e10646bc3f79ef5f9ccf12fc829f3
1 file changed