Merge pull request dotnet/corefx#10522 from hseok-oh/enableCross

set __CrossBuild in src/Native/build-native.sh automatically

Commit migrated from dotnet/corefx@6750e2b

Author: stephentoub

src/libraries/Native/build-native.sh

@@ -218,6 +218,27 @@ while :; do
     shift
 done
 
+# Set cross build
+CPUName=$(uname -p)
+# Some Linux platforms report unknown for platform, but the arch for machine.
+if [ $CPUName == "unknown" ]; then
+    CPUName=$(uname -m)
+fi
+case $CPUName in
+    i686)
+        if [ $__BuildArch != x86 ]; then
+            __CrossBuild=1
+            echo "Set CrossBuild for $__BuildArch build"
+        fi
+        ;;
+    x86_64)
+        if [ $__BuildArch != x64 ]; then
+            __CrossBuild=1
+            echo "Set CrossBuild for $__BuildArch build"
+        fi
+        ;;
+esac
+
 # Set the remaining variables based upon the determined build configuration
 __IntermediatesDir="$__rootbinpath/obj/$__BuildOS.$__BuildArch.$__BuildType/Native"
 __BinDir="$__rootbinpath/$__BuildOS.$__BuildArch.$__BuildType/Native"