Fiji Build: really reuse MiniMaven instances

The thinko in a86b5fa(Fiji Build: reuse MiniMaven instances) was that I
thought the SubFake instances were reused, but they are not.

A cleaner solution might be to hold the MiniMaven instance in the class
fiji.build.Fake. But in reality, I would like to get rid of Fiji Build
altogether in favor of MiniMaven, even getting rid of the submodules.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

src-plugins/fake/src/main/java/fiji/build/SubFake.java

@@ -105,7 +105,7 @@ public File getFakefile() {
 		return file.exists() ? file : null;
 	}
 
-	protected MiniMaven miniMaven;
+	protected static MiniMaven miniMaven;
 
 	public POM getPOM() {
 		if (pomRead)