KVM: selftests: Probe -no-pie with actual CFLAGS used to compile

Probe -no-pie with the actual set of CFLAGS used to compile the tests,
clang whines about -no-pie being unused if the tests are compiled with
-static.

  clang: warning: argument unused during compilation: '-no-pie'
  [-Wunused-command-line-argument]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221213001653.3852042-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/Makefile

@@ -195,7 +195,7 @@ CFLAGS += -Wall -Wstrict-prototypes -Wuninitialized -O2 -g -std=gnu99 \
 	$(KHDR_INCLUDES)
 
 no-pie-option := $(call try-run, echo 'int main(void) { return 0; }' | \
-        $(CC) -Werror -no-pie -x c - -o "$$TMP", -no-pie)
+        $(CC) -Werror $(CFLAGS) -no-pie -x c - -o "$$TMP", -no-pie)
 
 # On s390, build the testcases KVM-enabled
 pgste-option = $(call try-run, echo 'int main(void) { return 0; }' | \