Fix SBValue::FindValue for file static variables

Fix SBValue::FindValue for file static variables

This was just a thinko. The API StackFrame::GetVariableList takes a
bool for "get_file_globals" which if true will also find file statics
and file globals. But we only were passing that as true if the
ValueType was eValueTypeVariableGlobal, which meant that we never find
file statics. It's okay if we cast too wide a net when we do
GetVariableList as later on we check against the ValueType to filter
globals from statics.

There was a test that had a whole bunch of globals and tested
FindValue on all of them, but had no statics. So I just made one of
the globals a file static, which verifies the fix.

Differential Revision: https://reviews.llvm.org/D151392