Fix znc-buildmod on cygwin after rename of library

configure.ac

@@ -474,6 +474,7 @@ if test -z "$ISCYGWIN" ; then
 	appendMod -fPIC
 else
 	# But cygwin does want most of ZNC in a shared lib
+	# See https://cygwin.com/ml/cygwin-apps/2015-07/msg00108.html for the reasoning behind the name.
 	LIBZNC="cygznc-${LIBZNC_VERSION}.dll"
 	LIBZNCDIR="$bindir"
 fi

znc-buildmod.in

@@ -36,10 +36,11 @@ VERSION="@PACKAGE_VERSION@"
 # Ugly cygwin stuff :(
 LIBZNC="@LIBZNC@"
 LIBZNCDIR="@LIBZNCDIR@"
+LIBZNC_VERSION="@LIBZNC_VERSION@"
 if test "x" = "x$LIBZNC"; then
     LIBZNCFLAGS=""
 else
-    LIBZNCFLAGS="-L\"$LIBZNCDIR\" -lznc"
+    LIBZNCFLAGS="-L\"$LIBZNCDIR\" -lznc-$LIBZNC_VERSION"
 fi
 
 LDFLAGS="$LIBZNCFLAGS $LDFLAGS"