Add regression test for #644935

mono/tests/metadata-verifier/badrt_invalid_recursive_constraint.il

+.assembly extern mscorlib
+{
+  .ver 2:0:0:0
+  .publickeytoken = (B7 7A 5C 56 19 34 E0 89 ) // .z\V.4..
+}
+.assembly 'test'
+{
+  .custom instance void class [mscorlib]System.Runtime.CompilerServices.RuntimeCompatibilityAttribute::'.ctor'() =  (
+		01 00 01 00 54 02 16 57 72 61 70 4E 6F 6E 45 78   // ....T..WrapNonEx
+		63 65 70 74 69 6F 6E 54 68 72 6F 77 73 01       ) // ceptionThrows.
+
+  .hash algorithm 0x00008004
+  .ver  0:0:0:0
+}
+.module test.exe // GUID = {3B74EF02-761C-4A31-8BF2-54610FC3ACCC}
+
+
+  .class public auto ansi beforefieldinit N`2<(class N`2<int16, !T>) T,U>
+  	extends [mscorlib]System.Object
+  {
+
+    // method line 1
+    .method public hidebysig specialname rtspecialname 
+           instance default void '.ctor' ()  cil managed 
+    {
+        // Method begins at RVA 0x20ec
+	// Code size 7 (0x7)
+	.maxstack 8
+	IL_0000:  ldarg.0 
+	IL_0001:  call instance void object::'.ctor'()
+	IL_0006:  ret 
+    } // end of method N`2::.ctor
+
+  } // end of class N`2
+
+  .class public auto ansi beforefieldinit Bla
+  	extends [mscorlib]System.Object
+  {
+
+    // method line 2
+    .method public hidebysig specialname rtspecialname 
+           instance default void '.ctor' ()  cil managed 
+    {
+        // Method begins at RVA 0x20f4
+	// Code size 7 (0x7)
+	.maxstack 8
+	IL_0000:  ldarg.0 
+	IL_0001:  call instance void object::'.ctor'()
+	IL_0006:  ret 
+    } // end of method Bla::.ctor
+
+    // method line 3
+    .method public static hidebysig 
+           default void Main ()  cil managed 
+    {
+        // Method begins at RVA 0x20fc
+	.entrypoint
+	// Code size 1 (0x1)
+	.maxstack 8
+	IL_0000:  ret 
+    } // end of method Bla::Main
+
+  } // end of class Bla
+