build fails with libblacklist

[Rin Okuyama <okuyama%flex.phys.tohoku.ac.jp@localhost>]

Hi,

Building release fails with libblacklist:

  % ./build.sh -U -j16 tools release
  ...
  --- libblacklist.so.0.0 ---
  #     build  lib/libblacklist.so.0.0
  rm -f libblacklist.so.0.0
  /var/build/tools/bin/x86_64--netbsd-gcc  -Wl,-x -shared -Wl,-soname,libblacklist.so.0 -Wl,--warn-shared-textrel -Wl,-Map=libblacklist.so.0.map   --sysroot=/var/build/dest/amd64  -o libblacklist.so.0.0  -Wl,-rpath,/lib  -L=/lib  -Wl,--whole-archive libblacklist_pic.a  -Wl,--no-whole-archive -lpthread
  /var/build/tools/lib/gcc/x86_64--netbsd/4.8.5/../../../../x86_64--netbsd/bin/ld: cannot find -lpthread
  collect2: error: ld returned 1 exit status
  *** [libblacklist.so.0.0] Error code 1
  nbmake[7]: stopped in /var/build/src/external/bsd/blacklist/lib

The attached patch fixes this problem.
(But why the absence of libpthread cannot be detected by DPADD macro?)

Thanks,
Rin
========
--- src/lib/Makefile.orig	2015-12-31 22:49:45.000000000 +0900
+++ src/lib/Makefile	2015-12-31 23:23:07.000000000 +0900
@@ -52,7 +52,6 @@
 .endif
 
 SUBDIR+=	../external/bsd/am-utils/lib
-SUBDIR+=	../external/bsd/blacklist/lib
 
 SUBDIR+=	../external/bsd/flex/lib
 SUBDIR+=	../external/bsd/tre/lib
@@ -115,6 +114,7 @@
 SUBDIR+=	../crypto/external/bsd/netpgp/lib/verify # depends on libz
 .endif
 
+SUBDIR+=	../external/bsd/blacklist/lib		# depends on libpthread
 SUBDIR+=	../external/bsd/elftoolchain/lib/libdwarf # depends on libelf
 SUBDIR+=	../external/mit/lua/lib # depends on libm
 SUBDIR+=	libcurses	# depends on libterminfo