[msbuild] Don't try to bundle the BouncyCastle.Crypto library anymore.

A recent bump in the HotRestartVersion seems to be to a version of Hot Restart
that doesn't need/provide the BouncyCastle.Crypto library.

Unfortunately due to another issue, the bump didn't actually bring in the
updated Hot Restart version (the required NuGet packages weren't published to
a feed we subscribe to, so we silently [1] got a different version of the Hot
Restart packages). This means our build didn't break in the actual bump, but
only when the corresponding Hot Restart package versions were published to the
designated feeds (i.e. yesterday).

[1]: We got a warning, but no build error. xamarin#20043 fixes this problem.

msbuild/Makefile

@@ -69,7 +69,7 @@ TRANSLATED_ASSEMBLIES = $(foreach locale,$(LOCALIZATION_LANGUAGES),$(locale)/Xam
 LOCALIZATION_ASSEMBLIES = Xamarin.Localization.MSBuild
 IOS_TASK_ASSEMBLIES = Xamarin.iOS.Tasks $(LOCALIZATION_ASSEMBLIES)
 IOS_WINDOWS_TASK_ASSEMBLIES = Xamarin.iOS.Tasks.Windows
-IOS_WINDOWS_DEPENDENCIES = Xamarin.iOS.Windows.Client iSign.Core ws2_32 System.Diagnostics.Tracer BouncyCastle.Crypto System.Formats.Asn1 System.Buffers System.Memory System.Numerics.Vectors System.Runtime.CompilerServices.Unsafe System.Security.Cryptography.ProtectedData System.Security.Cryptography.Pkcs Microsoft.Win32.Registry System.Security.AccessControl System.Security.Principal.Windows
+IOS_WINDOWS_DEPENDENCIES = Xamarin.iOS.Windows.Client iSign.Core ws2_32 System.Diagnostics.Tracer System.Formats.Asn1 System.Buffers System.Memory System.Numerics.Vectors System.Runtime.CompilerServices.Unsafe System.Security.Cryptography.ProtectedData System.Security.Cryptography.Pkcs Microsoft.Win32.Registry System.Security.AccessControl System.Security.Principal.Windows
 IOS_WINDOWS_MOBILEDEVICE_TOOLS = iMobileDevice-net bz2 getopt ideviceactivation idevicebackup idevicebackup2 idevicecrashreport idevicedate idevicedebug idevicedebugserverproxy idevicediagnostics ideviceenterrecovery ideviceimagemounter ideviceinfo ideviceinstaller idevicename idevicenotificationproxy idevicepair ideviceprovision idevicerestore idevicescreenshot idevicesyslog idevice_id imobiledevice-net-lighthouse imobiledevice ios_webkit_debug_proxy iproxy irecovery irecovery libcharset libcurl LIBEAY32 libiconv libusb-1.0 libusb0 libxml2 lzma pcre pcreposix plist plistutil plist_cmp plist_test pthreadVC3 readline SSLEAY32 usbmuxd usbmuxd vcruntime140 zip zlib1
 
 IOS_DIRECTORIES =                                                                                           \