[CxxInterop] Add tests for static variables

[hlopko]

SR-12464

[gribozavr]

@swift-ci Please test

[gribozavr]

@swift-ci Please test Windows

[atrick]

@hlopko I'm not sure how this failure got through PR testing. Have you already fixed it or do I need to XFAIL the test?

https://ci.swift.org/job/oss-swift_tools-RA_stdlib-DA_test-device-non_executable/70/consoleFull

TEST 'Swift(iphoneos-armv7) :: Interop/Cxx/static/static-var-irgen.swift' FAILED

test/Interop/Cxx/static/static-var-irgen.swift:49:11: error: CHECK: expected string not found in input
// CHECK: call {{void @_ZN10NonTrivialC[12]Ei(%class.NonTrivial* @_ZL16staticNonTrivial, i32 1024)|%class.NonTrivial* @"??0NonTrivial@@qeaa@H@Z"(%class.NonTrivial* @staticNonTrivial, i32 1024)}}
^
:67:49: note: scanning from here
define internal void @__cxx_global_var_init.4() #0 section "__TEXT,__StaticInit,regular,pure_instructions" {
^

[hlopko]

Fix coming in #31530. Thanks for reporting.

As for why it was not caught by presubmits, I though we only have macos presubmits, no ios? Maybe @shahmishal can clarify?