libfuzzer-dotnet integration (#535)

src/integration-tests/libfuzzer-dotnet/problems/problems.cs

@@ -0,0 +1,15 @@
+using System;
+namespace Problems {
+  public static class Problems {
+    public static void Func(ReadOnlySpan<byte> data) {
+      var count = 0;
+      if (data.Length < 4) {
+         return;
+      }
+      if (data[0] == 0) { count++; } 
+      if (data[1] == 1) { count++; }
+      if (data[2] == 2) { count++; }
+      if (count >= 3) { throw new Exception("this is bad"); }
+    }
+  }
+}

src/integration-tests/libfuzzer-dotnet/problems/problems.csproj

@@ -0,0 +1,7 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.1</TargetFramework>
+  </PropertyGroup>
+
+</Project>