tools: Remove -Werror everywhere else

The previous changeset, e4f5949c44 ("tools: Add -Werror by default to all
tools/"), added "-Werror" to CFLAGS in tools/Rules.mk.  Remove it from
everywhere else now it is duplicated.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Henry Wang <Henry.Wang@arm.com>

tools/xentop/Makefile

@@ -13,7 +13,7 @@
 XEN_ROOT=$(CURDIR)/../..
 include $(XEN_ROOT)/tools/Rules.mk
 
-CFLAGS += -DGCC_PRINTF -Werror $(CFLAGS_libxenstat)
+CFLAGS += -DGCC_PRINTF $(CFLAGS_libxenstat)
 LDLIBS += $(LDLIBS_libxenstat) $(CURSES_LIBS) $(TINFO_LIBS) $(SOCKET_LIBS) -lm
 CFLAGS += -DHOST_$(XEN_OS)