rules.mak: Use -r instead of -Wl, -r to fix building when PIE is default

Building qemu fails in distributions where gcc enables PIE by default
(e.g. Debian unstable) with:

/usr/bin/ld: -r and -pie may not be used together

Use -r instead of -Wl,-r to avoid gcc passing -pie to the linker
when PIE is enabled and a relocatable object is passed.
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Message-Id: <20161127162817.15144-1-bunk@stusta.de>
Cc: qemu-stable@nongnu.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

rules.mak

@@ -93,7 +93,7 @@ module-common.o: CFLAGS += $(DSO_OBJ_CFLAGS)
 	$(if $(findstring /,$@),$(call quiet-command,cp $@ $(subst /,-,$@),"CP","$(subst /,-,$@)"))
 
 
-LD_REL := $(CC) -nostdlib -Wl,-r $(LD_REL_FLAGS)
+LD_REL := $(CC) -nostdlib -r $(LD_REL_FLAGS)
 
 %.mo:
 	$(call quiet-command,$(LD_REL) -o $@ $^,"LD","$(TARGET_DIR)$@")