Build stuff (#17)

* Add the V make parameter to enable verbose logging

Setting V to anything than 0 (zero) enables verbose logging for
{ms,x}build as well as exports MONO_OPTIONS=--debug to enable
stack traces should an exception be thrown when running mono.

To add/override MONO_OPTIONS simply set it on the command line when
invoking make, for instance:

    make V=1 MONO_OPTIONS="--trace"

* File.Move doesn't overwrite targets

File.Move will throw an exception whenever the target file exists.
Assuming that the task should overwrite the existing target files
for smooth operation, this change checks whether the target file
exists and, if so, deletes it prior to calling File.Move

Makefile

@@ -1,6 +1,16 @@
+V             ?= 0
 CONFIGURATION = Debug
 MSBUILD       = xbuild /p:Configuration=$(CONFIGURATION) $(MSBUILD_ARGS)
 
+ifneq ($(V),0)
+MONO_OPTIONS += --debug
+MSBUILD      += /v:d
+endif
+
+ifneq ($(MONO_OPTIONS),)
+export MONO_OPTIONS
+endif
+
 all:
 	$(MSBUILD)
 

src/Xamarin.Android.Tools.BootstrapTasks/Xamarin.Android.Tools.BootstrapTasks/UnzipDirectoryChildren.cs

@@ -112,8 +112,11 @@ async TTask ExtractFile (string tempDir, string sourceFile, string relativeDestD
 					Log.LogMessage (MessageImportance.Low, $"mv '{fse}' '{dest}'");
 					if (Directory.Exists (fse))
 						Process.Start ("/bin/mv", $@"""{fse}"" ""{dest}""").WaitForExit ();
-					else
+					else {
+						if (File.Exists (dest))
+							File.Delete (dest);
 						File.Move (fse, dest);
+					}
 				}
 			}
 		}