Restore LibGit2Sharp explicitly

This is a workaround for dotnet/sdk#1123

Author: AArnott

build.libgit2sharp.sh

@@ -14,8 +14,9 @@ export Configuration=release
 
 # On linux we don't pack because we can't build for net40.
 # We just build for CoreCLR and run tests for it.
+dotnet restore LibGit2Sharp
 dotnet restore LibGit2Sharp.Tests
-dotnet build LibGit2Sharp.Tests -f netcoreapp1.0 /property:ExtraDefine="$EXTRADEFINE"
+dotnet build LibGit2Sharp.Tests -f netcoreapp1.0 /property:ExtraDefine="$EXTRADEFINE" /fl /flp:verbosity=detailed
 dotnet test LibGit2Sharp.Tests/LibGit2Sharp.Tests.csproj -f netcoreapp1.0 --no-build
 
 exit $?