xen: Use MFLAGS for silent-mode detection

GNU make 4.4+ exposes variable overrides in MAKEFLAGS after "--" (e.g.
O=/path, FOO=bar). The silent-mode check searches for "s" and can match
an override value, forcing silent output even without -s.

Use MFLAGS for short options and filter out any long options before
searching for "s". This preserves -s detection while avoiding false
positives from overrides.

Signed-off-by: Bertrand Marquis <bertrand.marquis@arm.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: f2a31b7d7c
master date: 2026-02-10 10:22:53 +0100

xen/Makefile

@@ -113,10 +113,11 @@ else
     Q := @
 endif
 
-# If the user is running make -s (silent mode), suppress echoing of
-# commands
-
-ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
+# If the user is running make -s (silent mode), suppress echoing of commands.
+# Use MFLAGS (options only). MAKEFLAGS may include variable overrides after
+# “--” (GNU make 4.4 and newer), which can contain an “s” and falsely trigger
+# silent mode.
+ifneq ($(findstring s,$(filter-out --%,$(MFLAGS))),)
     quiet := silent_
 endif