Bump to Binutils v2.37

Changes: https://sourceware.org/pipermail/binutils/2021-July/117384.html

Upstream release message mentions numerous bug fixes, however doesn't
list them.  List of bugs in SourceWare bugzilla tagged with the 2.37
version:

https://sourceware.org/bugzilla/buglist.cgi?bug_status=RESOLVED&component=binutils&component=gas&component=ld&product=binutils&query_format=advanced&resolution=FIXED&version=2.37

build-tools/xaprepare/xaprepare/ConfigAndData/Configurables.cs

@@ -15,7 +15,7 @@ namespace Xamarin.Android.Prepare
 	//
 	partial class Configurables
 	{
-		const string BinutilsVersion                = "2.36.1-XA.1";
+		const string BinutilsVersion                = "2.37-XA.1";
 
 		const string MicrosoftOpenJDK11Version      = "11.0.10";
 		const string MicrosoftOpenJDK11Release      = "9.1";