[embedded] Avoid materializing generic functions for debuginfo purposes in embedded Swift

[kubamracek]

The attached testcase triggers a crash in embedded Swift mode because debuginfo ends up referencing a generic function (in the "inlined from" debuginfo data). This generic function is otherwise unused (and harmless in embedded Swift mode), but debuginfo generation will actually try to materialize it. Let's avoid that in embedded Swift.

Assertion failed: (!f->isGeneric()), function addLazyFunction, file GenDecl.cpp, line 1567.
...
3.	While evaluating request IRGenRequest(IR Generation for module main)
4.	While emitting IR SIL function "@$s4main15GenericSubClassC3fooyyFyycfU_AA11ImplementorC_Tg5".
 for expression at [/Users/kuba/swift-github-main/swift/test/embedded/generic-classes-debuginfo.swift:33:13 - line:33:33] RangeText="{ self.p.protofoo() "
...
 #8 0x00000001011c3090 swift::irgen::IRGenerator::addLazyFunction(swift::SILFunction*)
 #9 0x00000001011c54c4 swift::irgen::IRGenModule::getAddrOfSILFunction(swift::SILFunction*, swift::ForDefinition_t, bool, bool)
#10 0x00000001012cd910 (anonymous namespace)::IRGenDebugInfoImpl::getOrCreateScope(swift::SILDebugScope const*)
#11 0x00000001012d3cd0 (anonymous namespace)::IRGenDebugInfoImpl::getOrCreateContext(swift::DeclContext*)
#12 0x00000001012cdfa0 (anonymous namespace)::IRGenDebugInfoImpl::emitFunction(swift::SILDebugScope const*, llvm::Function*, swift::SILFunctionTypeRepresentation, swift::SILType, swift::DeclContext*, llvm::StringRef)
#13 0x00000001012cebc0 (anonymous namespace)::IRGenDebugInfoImpl::emitFunction(swift::SILFunction&, llvm::Function*)
#14 0x000000010130829c (anonymous namespace)::IRGenSILFunction::emitSILFunction()
#15 0x0000000101307a0c swift::irgen::IRGenModule::emitSILFunction(swift::SILFunction*)
#16 0x00000001011c0f4c swift::irgen::IRGenerator::emitGlobalTopLevel(std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>>> const&)
#17 0x00000001012c0d68 swift::IRGenRequest::evaluate(swift::Evaluator&, swift::IRGenDescriptor) const

[eeckstein]

lgtm!

[kubamracek]

@swift-ci please test

[kubamracek]

@swift-ci please smoke test macOS platform

[kubamracek]

@swift-ci please test macOS platform