Don't let first make steps depend on Makefile

Change-Id: I49558e934c5acb90d6c16b243a43579ec981d787
diff --git a/Makefile b/Makefile
index 1b96617..778d18d 100644
--- a/Makefile
+++ b/Makefile
@@ -2,11 +2,11 @@
 
 all: json
 
-./output/corpus.p5.xml: nor2tei.py Makefile
+./output/corpus.p5.xml: nor2tei.py
 	mkdir -p output
 	python nor2tei.py `find /export/coin/ICC/NO/Originaldaten -name "*.xml"`
 
-icc-nor.p5.xml: ./output/corpus.p5.xml Makefile
+icc-nor.p5.xml: ./output/corpus.p5.xml
 	perl -C255 -pe 's/([^>])\n/$1 /g; s/^\s*([^<])/$1/; s/\&gt /\&gt; /g;' $< | xmllint - > $@
 
 icc-nor.zip: icc-nor.p5.xml