Fix linking relocatable objects on Sparc

On Sparc, gcc implicitly passes --relax to the linker, but -r is
incompatible with this. Therefore, if --no-relax is supported, it should
be passed to the linker.

Signed-off-by: James Clarke <jrtc27@jrtc27.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

configure

@@ -31,6 +31,7 @@ TMPCXX="${TMPDIR1}/${TMPB}.cxx"
 TMPL="${TMPDIR1}/${TMPB}.lo"
 TMPA="${TMPDIR1}/lib${TMPB}.la"
 TMPE="${TMPDIR1}/${TMPB}.exe"
+TMPMO="${TMPDIR1}/${TMPB}.mo"
 
 rm -f config.log
 
@@ -4526,6 +4527,25 @@ if compile_prog "" "" ; then
     have_fsxattr=yes
 fi
 
+#################################################
+# Sparc implicitly links with --relax, which is
+# incompatible with -r, so --no-relax should be
+# given. It does no harm to give it on other
+# platforms too.
+
+# Note: the prototype is needed since QEMU_CFLAGS
+#       contains -Wmissing-prototypes
+cat > $TMPC << EOF
+extern int foo(void);
+int foo(void) { return 0; }
+EOF
+if ! compile_object ""; then
+  error_exit "Failed to compile object file for LD_REL_FLAGS test"
+fi
+if do_cc -nostdlib -Wl,-r -Wl,--no-relax -o $TMPMO $TMPO; then
+  LD_REL_FLAGS="-Wl,--no-relax"
+fi
+
 ##########################################
 # End of CC checks
 # After here, no more $cc or $ld runs
@@ -5529,6 +5549,7 @@ else
 fi
 echo "LDFLAGS=$LDFLAGS" >> $config_host_mak
 echo "LDFLAGS_NOPIE=$LDFLAGS_NOPIE" >> $config_host_mak
+echo "LD_REL_FLAGS=$LD_REL_FLAGS" >> $config_host_mak
 echo "LIBS+=$LIBS" >> $config_host_mak
 echo "LIBS_TOOLS+=$libs_tools" >> $config_host_mak
 echo "EXESUF=$EXESUF" >> $config_host_mak

rules.mak

@@ -95,7 +95,7 @@ module-common.o: CFLAGS += $(DSO_OBJ_CFLAGS)
 	$(if $(findstring /,$@),$(call quiet-command,cp $@ $(subst /,-,$@), "  CP    $(subst /,-,$@)"))
 
 
-LD_REL := $(CC) -nostdlib -Wl,-r
+LD_REL := $(CC) -nostdlib -Wl,-r $(LD_REL_FLAGS)
 
 %.mo:
 	$(call quiet-command,$(LD_REL) -o $@ $^,"  LD -r $(TARGET_DIR)$@")