C#: Fixup tests.

Author: michaelnebel

csharp/ql/lib/semmle/code/cil/ConsistencyChecks.qll

@@ -617,7 +617,13 @@ class ExprMissingType extends InstructionViolation {
     not instruction instanceof Opcodes::Arglist and
     not instruction instanceof Opcodes::Refanytype and
     instruction.getPushCount() >= 1 and
-    count(instruction.getType()) != 1
+    count(instruction.getType()) != 1 and
+    // OS specific (osx) specific inconsistency
+    not instruction
+        .getImplementation()
+        .getMethod()
+        .hasFullyQualifiedName("System.Runtime.InteropServices.RuntimeInformation",
+          "get_OSDescription")
   }
 
   override string getMessage() { result = "Expression is missing getType()" }