libxdp: fix build with clang 18

Use compiler to link.  While here, retire LD from configure since this
is not used anymore

Signed-off-by: Renato Botelho do Couto <renato@netgate.com>

configure

@@ -59,7 +59,6 @@ check_toolchain()
 
     : ${PKG_CONFIG:=pkg-config}
     : ${CC=gcc}
-    : ${LD=ld}
     : ${OBJCOPY=objcopy}
     : ${CLANG=clang}
     : ${LLC=llc}
@@ -73,7 +72,7 @@ check_toolchain()
     CLANG=$(find_tool clang "$CLANG")
     LLC=$(find_tool llc "$LLC")
 
-    for TOOL in $PKG_CONFIG $CC $LD $OBJCOPY $CLANG $LLC $M4 $READELF; do
+    for TOOL in $PKG_CONFIG $CC $OBJCOPY $CLANG $LLC $M4 $READELF; do
         if [ ! $(command -v ${TOOL} 2>/dev/null) ]; then
             echo "*** ERROR: Cannot find tool ${TOOL}" ;
             exit 1;
@@ -130,7 +129,6 @@ check_toolchain()
 
     echo "PKG_CONFIG:=${PKG_CONFIG}" >>$CONFIG
     echo "CC:=${CC}" >>$CONFIG
-    echo "LD:=${LD}" >>$CONFIG
     echo "OBJCOPY:=${OBJCOPY}" >>$CONFIG
     echo "CLANG:=${CLANG}" >>$CONFIG
     echo "LLC:=${LLC}" >>$CONFIG

lib/libxdp/Makefile

@@ -131,7 +131,7 @@ $(TEMPLATED_SOURCES): %.c: %.c.in Makefile
 	$(QUIET_M4)$(M4) $(DEFINES) $< > $@ || ( ret=$$?; rm -f $@; exit $$ret )
 
 $(EMBEDDED_XDP_OBJS): %.embed.o: %.o
-	$(QUIET_GEN)$(LD) -r -b binary -o $@ -z noexecstack --format=binary $<
+	$(QUIET_CC)$(CC) -r -nostdlib -Wl,-z,noexecstack,--format=binary -o $@ $<
 	$(Q)$(OBJCOPY)  --rename-section .data=.rodata,alloc,load,readonly,data,contents $@
 
 $(XDP_OBJS): %.o: %.c $(BPF_HEADERS) $(LIBMK)