Add default Skunware libstdc++.so path to LDFLAGS for Solaris.

src/build/Common.gmake

@@ -221,6 +221,7 @@ endif
 # OS Specific Flags
 ifeq ($(os),sunos)    # Solaris
  CFLAGS	+= -D__solaris__ -DNEEDS_DAEMON -DNEEDS_FORKPTY -DNEEDS_SETENV -DNEEDS_CFMAKERAW
+ LDFLAGS	+=	-L/opt/sfw/lib
 endif
 ifeq ($(os),netbsd)	# NetBSD
  CFLAGS	+=	-D__unix__ -I/usr/pkg/include