[docs] Keep job running even if .qch files are not present.

Currently, the job fails when it cannot find .qch files to compress.
Now, the error message is printed, but the upload of the documentation
proceeds.

Author: hageboeck

documentation/doxygen/Makefile

@@ -78,8 +78,8 @@ doxygen: filter pyzdoc htmlfooter
 	./makeinput.sh
 	doxygen
 	bash ./CleanNamespaces.sh
-	gzip $(DOXYGEN_IMAGE_PATH)/ROOT.tag
-	gzip $(DOXYGEN_IMAGE_PATH)/ROOT.qch
+	gzip $(DOXYGEN_IMAGE_PATH)/ROOT.tag || true
+	gzip $(DOXYGEN_IMAGE_PATH)/ROOT.qch || true
 	rm -rf files c1* *.ps *.eps *.png *.jpg *.tex *.svg *.pdf *.root *.xpm *.out *.dat *.dtd *.dot *.txt *.csv *.log *.rs
 	rm -rf listofclass.sh tmva* data* result* config* test* Roo* My* Freq*
 	rm -f Doxyfile_INPUT filter htmlfooter.html MDF.C pca.C