contrib/jpeg: use our own hosting since their servers blocks downloads with curl (close #11048)

wget and mainstream web browsers are not affected.

contrib/src/jpeg/rules.mak

 # jpeg
 
 JPEG_VERSION := 9
-JPEG_URL := http://www.ijg.org/files/jpegsrc.v$(JPEG_VERSION).tar.gz
+# JPEG_URL := http://www.ijg.org/files/jpegsrc.v$(JPEG_VERSION).tar.gz
+JPEG_URL := http://download.videolan.org/pub/contrib/jpegsrc.v$(JPEG_VERSION).tar.gz
 
 $(TARBALLS)/jpegsrc.v$(JPEG_VERSION).tar.gz:
 	$(call download,$(JPEG_URL))