cppcms: does not build on static library only, needs dlopen()

Fixes:

  http://autobuild.buildroot.org/results/5ee/5ee69eb7492fbd462124d7a23b5b79003fc1dd64/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/cppcms/Config.in

@@ -5,6 +5,7 @@ config BR2_PACKAGE_CPPCMS
 	select BR2_PACKAGE_LIBGCRYPT
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on BR2_TOOLCHAIN_HAS_THREADS
+	depends on !BR2_PREFER_STATIC_LIB # dlopen()
 	help
 	  CppCMS is a Free High Performance Web Development Framework
 	  (not a CMS) aimed for Rapid Web Application Development. It
@@ -38,5 +39,6 @@ comment "icu support needs a toolchain w/ wchar"
 
 endif
 
-comment "cppcms needs a toolchain w/ C++, threads"
-	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS
+comment "cppcms needs a toolchain w/ C++, threads, dynamic library"
+	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS || \
+		BR2_PREFER_STATIC_LIB