Make libxnet.so a symlink to libc.so. This makes -lxnet a no-op, as

POSIX requires for the c99 compiler.

(In fact, our c99(1) already ignores -lxnet; but our make(1) doesn't set
${CC} correctly, and our cc(1) treats xnet like any other library.)

Reviewed by:	kib

lib/libc/Makefile

@@ -26,6 +26,7 @@ LIBC_ARCH=${MACHINE_CPUARCH}
 LIB=c
 SHLIB_MAJOR= 7
 SHLIB_LDSCRIPT=libc.ldscript
+SHLIB_LDSCRIPT_LINKS=libxnet.so
 WARNS?=	2
 CFLAGS+=-I${LIBC_SRCTOP}/include -I${LIBC_SRCTOP}/../../include
 CFLAGS+=-I${LIBC_SRCTOP}/${LIBC_ARCH}

share/mk/bsd.lib.mk

@@ -368,6 +368,9 @@ _libinstall:
 	${INSTALL} -S -C -o ${LIBOWN} -g ${LIBGRP} -m ${LIBMODE} \
 	    ${_INSTALLFLAGS} ${SHLIB_LINK:R}.ld \
 	    ${DESTDIR}${_LIBDIR}/${SHLIB_LINK}
+.for _SHLIB_LINK_LINK in ${SHLIB_LDSCRIPT_LINKS}
+	${INSTALL_SYMLINK} ${SHLIB_LINK} ${DESTDIR}${_LIBDIR}/${_SHLIB_LINK_LINK}
+.endfor
 .else
 .if ${_SHLIBDIR} == ${_LIBDIR}
 	${INSTALL_SYMLINK} ${SHLIB_NAME} ${DESTDIR}${_LIBDIR}/${SHLIB_LINK}