deps/Makefile: Use "git remote set-url" to catch URL changes

In the past, we sometimes had to switch a repository URL (e.g. from
official git repo ot osmocom fork with patches/fixes).  The existing
Makefile didn't pick this up during "make update".  Let's use "git
remote set-url" to always update the remote URL before doing the "git
fetch".

Change-Id: I1d699ad5087f438e64b84c2e5c6e7320cb9457f6
diff --git a/deps/Makefile b/deps/Makefile
index 6f975f2..ccf2bdb 100644
--- a/deps/Makefile
+++ b/deps/Makefile
@@ -55,7 +55,7 @@
 
 .PHONY:$(1)/update
 $(1)/update: $(1)
-	(cd $(1) && git fetch && git checkout -f -B master origin/master)
+	(cd $(1) && git remote set-url origin $(2)/$(1) && git fetch && git checkout -f -B master origin/master)
 
 .PHONY: $(1)/clean
 $(1)/clean: