Rename the "tools" programs to also have the "git-" prefix

Hey, people are using them, and we have an install target for them, so
make sure that we can actually install them sanely without disturbing
the namespace.

tools/Makefile

@@ -10,8 +10,11 @@ prefix=$(HOME)
 bin=$(prefix)/bin
 # dest=
 
-PROGRAMS=mailsplit mailinfo
+PROGRAMS=git-mailsplit git-mailinfo
-SCRIPTS=applymbox applypatch
+SCRIPTS=git-applymbox git-applypatch
+
+git-%: %.c
+	$(CC) $(CFLAGS) -o $@ $(filter %.c,$^)
 
 all: $(PROGRAMS)