x86emul/test: correct compiler checking and avoid it when merely cleaning

The error messages that the compiler may emit can be confusing.

The check was also the wrong way round in case multiple make targets are
specified: We want to do the check whenever targets other than the running
and cleaning ones are specified.

Fixes: 05f4cc2192 ("x86emul: suppress default test harness build with incapable compiler")
Fixes: d5997399b7 ("x86emul: suppress "not built" warning for test harness'es run targets")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

tools/tests/x86_emulator/Makefile

@@ -98,7 +98,7 @@ avx512bw-opmask-vecs := 4 8
 # partially even with older compilers.
 TARGET-y := $(TARGET)
 
-ifeq ($(filter run%,$(MAKECMDGOALS)),)
+ifneq ($(filter-out run% clean% distclean,$(MAKECMDGOALS)),)
 
 define isa-check-cc
 TARGET-$(shell echo 'int i;' | $(CC) -x c -c -o /dev/null -m$(1) - || echo y) :=