Disable non-global template support for other compilers than DMD

[SSoulaimane]

Until GDC and LDC catch up.

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[12345swordy]

cc @WalterBright @thewilsonator
Is this an reasonable compromise?

[wilzbach]

I'm sorry, but I don't see how this would be useful as the error message for the tests will be different for gdc and LDC, so they have to patch things anyhow. Also, LDC has already done this and released a beta.

[ibuclaw]

Also, LDC has already done this and released a beta.

Citation?

[wilzbach]

Also, LDC has already done this and released a beta.

Citation?

ldc-developers/ldc#3093 (comment)

With this. I was referring to the sentence before (this PR and its disabling of the feature).

[ibuclaw]

@wilzbach - Thanks for clarifying. 'This' was rather ambiguous in your context. :-)

[Geod24]

The feature has been deprecated in v2.096.0: https://dlang.org/changelog/2.096.0.html#deprecate_dualcontext