Fix System.Reflection.Emit.ILGeneration.Tests

Modified the Generator class to use locks to ensure thread safety with
using Random. Enforced missing .NET coding guidelines, from the
codeformatter tool.

Author: Lakshmi Priya Sekar

src/System.Reflection.Emit.ILGeneration/tests/CustomAttributeBuilder/CustomAttributeBuilderCtor1.cs

@@ -39,7 +39,7 @@ public void PosTest2()
         public void PosTest3()
         {
             string str = "PosTest3";
-            bool b = TestLibrary.Generator.GetByte(-55) > Byte.MaxValue / 2;
+            bool b = TestLibrary.Generator.GetByte() > byte.MaxValue / 2;
 
             Type[] ctorParams = new Type[] { typeof(string), typeof(bool) };
             object[] paramValues = new object[] { str, b };
@@ -144,4 +144,4 @@ public class TestConstructor
         static TestConstructor() { }
         internal TestConstructor(bool b) { }
     }
-}
+}