A static var of interface type round-tripped through static methods
(THolder.SetIt(X: IThing) / THolder.GetIt: IThing) was miscompiled on
both backends. The 2-slot fat-pointer global slot itself was correct;
the bugs were in the static-CALL path.
QBE: a static method whose first parameter is interface-typed emitted
'call $T_M(, l obj, l itab)'. The interface argument fragment carries a
leading ', ' (it is normally appended after Self or a preceding arg), and
the static-call argument loop did not strip it, so the first argument
began with a comma and QBE rejected it as an invalid class specifier.
Strip the leading ', ' in that branch, matching the existing
EmitMethodCall var-arg/interface precedent.
Native: a static method returning an interface routed through
EmitClassIntfSretMethodCall (ResolvedClassType is the owning class, a
class type), which loaded the bare type name as a global Self and emitted
an undefined reference to the class symbol at external-cc link time (the
internal/driver linker masked it). Add an IsStaticCall branch that emits
the plain free-function interface-sret ABI with no receiver, mirroring
the non-Self arm of EmitIntfSretCall.
Tests: TestIR_StaticCall_InterfaceArg_NoLeadingComma asserts the QBE call
has no leading comma; TestRun_StaticVar_InterfaceStore compiles and runs
the SetIt/GetIt round-trip on both backends.
e950814a34