[LLDB][NativePDB] Ignore functions with no type in name lookup (#153382)

Some functions don't have the `FunctionType` set. We can't look these up
and won't be able to call them, so ignore them when caching the function
names.

This does fix the failures caused by
https://github.com/llvm/llvm-project/pull/153160 mentioned in
https://github.com/llvm/llvm-project/pull/153160#issuecomment-3183062431.
However, in `lldb-shell::msstl_smoke.cpp` there's another failure not
introduced by #153160 (fixed with #153386).

lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp

diff --git a/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp b/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
index 108e439..112eb06 100644
--- a/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
+++ b/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
@@ -1688,7 +1688,7 @@
         llvm::cantFail(SymbolDeserializer::deserializeAs<ProcSym>(*iter));
     if ((proc.Flags & ProcSymFlags::IsUnreachable) != ProcSymFlags::None)
       continue;
-    if (proc.Name.empty())
+    if (proc.Name.empty() || proc.FunctionType.isSimple())
       continue;
 
     // The function/procedure symbol only contains the demangled name.