[mono-sdks] Fix Linux build

LLVM would fail to build on Linux because it would try to compile with a --host finishing with "apple-darwin10". The fix consist in testing if we are currently building on macOS (apple-darwin10) or Linux (linux-gnu).

We also make sure to pass to the Mono SDKs the path to `external/llvm`, thus avoiding cloning it again in `external/mono/sdks/builds/toolchains/llvm`.

Author: luhenry

external/mono

@@ -36,6 +36,13 @@
   <PropertyGroup>
     <_MonoSdksConfiguration Condition=" '$(Configuration)' == 'Release' ">release</_MonoSdksConfiguration>
     <_MonoSdksConfiguration Condition=" '$(Configuration)' != 'Release' ">debug</_MonoSdksConfiguration>
+
+    <_MonoSdksAndroidToolchainPrefix>$([System.IO.Path]::GetFullPath ('$(AndroidToolchainDirectory)\toolchains'))</_MonoSdksAndroidToolchainPrefix>
+    <_MonoSdksLlvmSrc>$([System.IO.Path]::GetFullPath ('$(MSBuildThisFileDirectory)..\..\external\llvm'))</_MonoSdksLlvmSrc>
+    <_MonoSdksMxePrefix>$(AndroidMxeFullPath)</_MonoSdksMxePrefix>
+    <_MonoSdksMxeSrc>$([System.IO.Path]::GetFullPath ('$(MSBuildThisFileDirectory)..\..\external\mxe'))</_MonoSdksMxeSrc>
+
+    <_MonoSdksParameters>CONFIGURATION=$(_MonoSdksConfiguration) IGNORE_PACKAGE_MXE=true IGNORE_PACKAGE_LLVM=true ANDROID_TOOLCHAIN_PREFIX=&quot;$(_MonoSdksAndroidToolchainPrefix)&quot; LLVM_SRC=&quot;$(_MonoSdksLlvmSrc)&quot; MXE_PREFIX=&quot;$(_MonoSdksMxePrefix)&quot; MXE_SRC=&quot;$(_MonoSdksMxeSrc)&quot;</_MonoSdksParameters>
   </PropertyGroup>
   <PropertyGroup>
     <ForceBuildDependsOn>
@@ -199,7 +206,7 @@
           Condition=" '$(_LlvmNeeded)' != '' ">
     <Exec
         Condition=" '%(_LlvmRuntime.UseMonoSdks)' != 'False' "
-        Command="make $(MakeConcurrency) package-llvm-%(_LlvmRuntime.Identity) CONFIGURATION=$(_MonoSdksConfiguration)"
+        Command="make $(MakeConcurrency) package-llvm-%(_LlvmRuntime.Identity) $(_MonoSdksParameters)"
         IgnoreStandardErrorWarningFormat="True"
         WorkingDirectory="$(MonoSourceFullPath)\sdks\builds"
     />
@@ -441,7 +448,7 @@
       Outputs="@(_RuntimeSource);@(_MonoBinarySource);@(_ProfilerSource);@(_MonoPosixHelperSource);@(_RuntimeEglibHeaderSource);@(_MonoBtlsSource);@(_BclTestOutput)">
     <Exec
         Condition=" '%(_MonoRuntime.UseMonoSdks)' != 'False' And '%(_MonoRuntime.DoBuild)' == 'true' "
-        Command="make $(MakeConcurrency) package-android-%(_MonoRuntime.Identity) CONFIGURATION=$(_MonoSdksConfiguration) ANDROID_TOOLCHAIN_PREFIX=&quot;$(AndroidToolchainDirectory)\toolchains&quot;"
+        Command="make $(MakeConcurrency) package-android-%(_MonoRuntime.Identity) $(_MonoSdksParameters)"
         IgnoreStandardErrorWarningFormat="True"
         WorkingDirectory="$(MonoSourceFullPath)\sdks\builds"
     />
@@ -881,13 +888,13 @@
       AfterTargets="Clean">
     <Exec
         Condition=" '%(_MonoRuntime.UseMonoSdks)' != 'False' "
-        Command="make $(MakeConcurrency) clean-android-%(_MonoRuntime.Identity) CONFIGURATION=$(_MonoSdksConfiguration)"
+        Command="make $(MakeConcurrency) clean-android-%(_MonoRuntime.Identity) $(_MonoSdksParameters)"
         IgnoreStandardErrorWarningFormat="True"
         WorkingDirectory="$(MonoSourceFullPath)\sdks\builds"
     />
     <Exec
         Condition=" '%(_LlvmRuntime.UseMonoSdks)' != 'False' "
-        Command="make $(MakeConcurrency) clean-llvm-%(_LlvmRuntime.Identity) CONFIGURATION=$(_MonoSdksConfiguration)"
+        Command="make $(MakeConcurrency) clean-llvm-%(_LlvmRuntime.Identity) $(_MonoSdksParameters)"
         IgnoreStandardErrorWarningFormat="True"
         WorkingDirectory="$(MonoSourceFullPath)\sdks\builds"
     />