proxychains-ng: needs dynamic library support

Fix below build error if BR2_PREFER_STATIC_LIB is set:

src/libproxychains.c:34:19: fatal error: dlfcn.h: No such file or directory
compilation terminated.
make[1]: *** [src/libproxychains.o] Error 1

In additional, the README file also mentions that this program works only on
dynamically linked programs.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/proxychains-ng/Config.in

@@ -1,10 +1,11 @@
 config BR2_PACKAGE_PROXYCHAINS_NG
 	bool "proxychains-ng"
 	depends on BR2_TOOLCHAIN_HAS_THREADS
+	depends on !BR2_PREFER_STATIC_LIB
 	help
 	  Force any tcp connections to flow through a proxy (or proxy chain)
 
 	  https://github.com/rofl0r/proxychains
 
-comment "proxychains-ng needs a toolchain with thread support"
-	depends on !BR2_TOOLCHAIN_HAS_THREADS
+comment "proxychains-ng needs a toolchain with thread and dynamic library support"
+	depends on !BR2_TOOLCHAIN_HAS_THREADS || BR2_PREFER_STATIC_LIB