Config.mk: correct gcc5 check

Passing the -dumpversion option to gcc may only print the major version
(my system 4.x.y printed major and minor, which in nowaday's scheme is
then indeed just 5 for 5.x, which in turn is what my secondary system
compiler does).

Fixes: 40458f7525 ("Xen: Update compiler baseline checks")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

Config.mk

@@ -125,8 +125,8 @@ define cc-ver-check-closure
     endif
 endef
 
-# Require GCC v5.1 as the project global baseline
+# Require GCC v5 as the project global baseline
-check-$(gcc) = $(call cc-ver-check,CC,0x050100,"Xen requires at least GCC 5.1")
+check-$(gcc) = $(call cc-ver-check,CC,0x050000,"Xen requires at least GCC 5")
 $(eval $(check-y))
 
 ld-ver-build-id = $(shell $(1) --build-id 2>&1 | \