[build] Use a system mono/2018-06 debug build (#2440)

Context: https://github.com/mono/mono/pull/11706
Context: https://github.com/xamarin/xamarin-android/pull/2357
Context: https://jenkins.mono-project.com/view/Xamarin.Android/job/xamarin-android/1239/console

Sometimes a Jenkins build will timeout when executing the
xamarin-android unit tests.  The timeout *appears* to occur when
`mono` is used to execute a process, the process "finishes," but the
process never actually *exits*, thus "hanging".

For example, [consider this build log fragment][0] (with timestamps):

	23:37:48   Build succeeded.
	23:37:48       0 Warning(s)
	23:37:48       0 Error(s)
	23:37:48
	23:37:48   Time Elapsed 01:23:14.60
	02:37:48 Build timed out (after 180 minutes). Marking the build as aborted.

The "Build succeeded" message comes from an `msbuild` invocation.
Once `msbuild` finished, we would expect it's process to exit.
*It didn't*.  Instead, the underlying `mono` process is *not* exiting,
presumably deadlocked, until the overall job times out and is killed.

Attempt to help identify the hang by using a "debug" mono/2018-08
system mono, built from [Mono PR #11706][1], which prints out
additional messages around child process use:

	diff --git a/mono/metadata/w32process-unix.c b/mono/metadata/w32process-unix.c
	index 2db5dea7a705..fbd4731cacb2 100644
	--- a/mono/metadata/w32process-unix.c
	+++ b/mono/metadata/w32process-unix.c
	@@ -2096,7 +2095,7 @@ process_create (const gunichar2 *appname, const gunichar2 *cmdline,
	 	if (argv)
	 		g_strfreev (argv);
 
	-	mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_IO_LAYER_PROCESS, "%s: returning handle %p for pid %d", __func__, handle, pid);
	+	g_printerr ("XXX-MONO: %s: returning handle %p for pid %d from %d\n", __func__, handle, pid, getpid());

This will hopefully allow @lewurm to continue investigations.

[0]: https://jenkins.mono-project.com/view/Xamarin.Android/job/xamarin-android/1237/console
[1]: https://github.com/mono/mono/pull/11706

Configuration.props

@@ -71,8 +71,8 @@
     <JavaInteropSourceDirectory Condition=" '$(JavaInteropSourceDirectory)' == '' ">$(MSBuildThisFileDirectory)external\Java.Interop</JavaInteropSourceDirectory>
     <LlvmSourceDirectory Condition=" '$(LlvmSourceDirectory)' == '' ">$(MSBuildThisFileDirectory)external\llvm</LlvmSourceDirectory>
     <MonoSourceDirectory>$(MSBuildThisFileDirectory)external\mono</MonoSourceDirectory>
-    <MonoRequiredMinimumVersion Condition=" '$(MonoRequiredMinimumVersion)' == '' ">5.16.0</MonoRequiredMinimumVersion>
-    <MonoRequiredMaximumVersion Condition=" '$(MonoRequiredMaximumVersion)' == '' ">5.17.0</MonoRequiredMaximumVersion>
+    <MonoRequiredMinimumVersion Condition=" '$(MonoRequiredMinimumVersion)' == '' ">5.16.0.229</MonoRequiredMinimumVersion>
+    <MonoRequiredMaximumVersion Condition=" '$(MonoRequiredMaximumVersion)' == '' ">5.16.0.230</MonoRequiredMaximumVersion>
     <IgnoreMaxMonoVersion Condition=" '$(IgnoreMaxMonoVersion)' == '' ">True</IgnoreMaxMonoVersion>
     <MonoRequiredDarwinMinimumVersion>$(MonoRequiredMinimumVersion).0</MonoRequiredDarwinMinimumVersion>
     <LinkerSourceDirectory>$(MSBuildThisFileDirectory)external\mono\external\linker</LinkerSourceDirectory>

Makefile

@@ -183,6 +183,8 @@ $(eval $(call CREATE_THIRD_PARTY_NOTICES_RULE,ThirdPartyNotices.txt,foundation,F
 $(eval $(call CREATE_THIRD_PARTY_NOTICES_RULE,bin/$(CONFIGURATION)/lib/xamarin.android/ThirdPartyNotices.txt,$(THIRD_PARTY_NOTICE_LICENSE_TYPE),True,False))
 
 run-all-tests:
+	@echo "PRINTING MONO VERSION"
+	mono --version
 	$(call MSBUILD_BINLOG,run-all-tests) $(TEST_TARGETS) /t:RunAllTests
 	$(MAKE) run-api-compatibility-tests
 

build-tools/dependencies/dependencies.projitems

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
-    <_DarwinMonoFramework>MonoFramework-MDK-5.16.0.106.macos10.xamarin.universal.pkg</_DarwinMonoFramework>
+    <_DarwinMonoFramework>MonoFramework-MDK-pr@8b63979dafb-dirty-5.16.0.229.macos10.xamarin.universal.pkg</_DarwinMonoFramework>
     <_AptGetInstall>apt-get -f -u install</_AptGetInstall>
   </PropertyGroup>
   <ItemGroup>
@@ -59,7 +59,7 @@
       <MaximumVersion Condition=" '$(IgnoreMaxMonoVersion)' == '' Or '$(IgnoreMaxMonoVersion)' == 'False' " >$(MonoRequiredMaximumVersion)</MaximumVersion>
       <DarwinMinimumVersion>$(MonoRequiredDarwinMinimumVersion)</DarwinMinimumVersion>
       <CurrentVersionCommand>$(MSBuildThisFileDirectory)..\scripts\mono-version</CurrentVersionCommand>
-      <DarwinMinimumUrl>https://xamjenkinsartifact.azureedge.net/build-package-osx-mono/2018-06/78/341142d7656f43239a041b2c44f00acfb8fa7c59/$(_DarwinMonoFramework)</DarwinMinimumUrl>
+      <DarwinMinimumUrl>https://xamjenkinsartifact.azureedge.net/build-package-osx-mono-pullrequest/pr/263/8b63979dafb7e2d275680abe26a6e27d1bdf302a/$(_DarwinMonoFramework)</DarwinMinimumUrl>
       <DarwinInstall>installer -pkg "$(AndroidToolchainCacheDirectory)\$(_DarwinMonoFramework)" -target /</DarwinInstall>
     </RequiredProgram>
   </ItemGroup>