[build] Fix the MSBuild build #1232
                
     Merged
            
            
          
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The
msbuild-based Jenkins job job has beenfailing a lot recently:
The cause of the error is that when there is no prebuilt mono runtime
to download, this file does not exist:
The above file is created by the
build-tools/scripts/mono-runtimes.mdprojbuild, andmono-runtimes.mdprojis not being built. Without a mono build,there is no
MonoAndroid/v1.0framework, and everything fails.I don't know when this actually broke, or what change is responsible.
(It works with
xbuild!)Attempt to improve reliability by adding
mono-runtimes.mdprojto$(MSBUILD_PREPARE_PROJS). This will cause themsbuild-based buildto explicitly build
mono-runtimes.mdprojbefore attempting tobuild
Xamarin.Android.Build.Tasks.csprojorXamarin.Android.sln.