Don't let PDBSourceLineWriter::GetSymbolFunctionName return empty function names

src/common/windows/pdb_source_line_writer.cc

Index: src/common/windows/pdb_source_line_writer.cc
diff --git a/src/common/windows/pdb_source_line_writer.cc b/src/common/windows/pdb_source_line_writer.cc
index f0edb721c07e86bd9658a984be55e6bf23749dbe..01f4ce3b7519a8d55d2044e27ec3851af4492131 100644
--- a/src/common/windows/pdb_source_line_writer.cc
+++ b/src/common/windows/pdb_source_line_writer.cc
@@ -975,6 +975,16 @@ bool PDBSourceLineWriter::GetSymbolFunctionName(IDiaSymbol *function,
       fprintf(stderr, "failed to get function name\n");
       return false;
     }
+
+    // It's possible for get_name to return an empty string, so
+    // special-case that.
+    if (wcscmp(*name, L"") == 0) {
+      SysFreeString(*name);
+      // dwarf_cu_to_module.cc uses "<name omitted>", so match that.
+      *name = SysAllocString(L"<name omitted>");
+      return true;
+    }
+
     // If a name comes from get_name because no undecorated form existed,
     // it's already formatted properly to be used as output.  Don't do any
     // additional processing.