Fix binary package build script on OS X

Author: dontpanic92

utils/build_binary_package.sh

@@ -26,7 +26,7 @@ done;
 
 if [ "$1" == "darwin" ]; then
     # cocoa/power.mm compiled twice! Delete one of them
-    rm baselib_cocoa_power_darwin_amd64.o
+    rm baselib_cocoa_power.o
 fi;
 
 # Windows has a limit of maximum command line characers. If we simply copy 
@@ -62,6 +62,7 @@ mv *.syso $GOPATH/src/github.com/dontpanic92/wxGo/wx/
 export GOARCH=$2
 export GOOS=$1
 export CGO_ENABLED=1
+go version
 go env
 go install -tags "wxgo_binary_package_build" -x github.com/dontpanic92/wxGo/wx